I just recently replaced a number of parts, and now the truck will miss at both idle and through all rpm ranges while crusing.
Parts:
cloyes timing chain, removed old tensioner (broken) and did NOT add a new tensioner. (Didn't think tensioner was needed with this set?!)
belly pan gasket
intake gaskets
valve cover gaskets (Fel-Pro metallic looking ones. I used red RTV around the water ports ONLY and the rest of the gasket was dry)
fuel injector O-rings (thin coat of engine oil only)
cleaned IAC (idle solenoid)
sort-of cleaned the throttle body(scrubbed the bores with toothbrush and carb cleaner, but did not clean the ports or blow out w/ compressed air) I resued the old TB gasket, and just put a very thin coat of gasket cement on each side before bolting back on.
new cap and rotor
cleaned and reused old spark plug wires

I've checked most of the hoses for vaccuum leaks, but the engine increases rpm when unplugging hoses?

One huge problem with this engine was sludge. IT has 180,000 miles on it, and the belly pan probably leaked for a long time of that. Sludge in the lifter valley and under the vavle covers was BADDD. I used the shop vac to get most of it out, but I'm wondering now if I managed to push some of the sludge farther down into the engine. I removed the rockers while cleaning out the sludge as well.

The reason I tore down the engine was that it was using coolant (intake gasket leak), but it still idled pretty good and no problems at speed. Plus the fact the timing chain was ratteling pretty bad.

I'm thinking I should pull the plugs and look for signs of coolant on the plugs again.

What else? I really don't want to tear it apart again until I have some ideas as to what may be wrong.

Sorry for the long post, but I'm hoping someone can help. Thanks

 

first check the that you have the wires put back on correctly, it sounds dumb but i make the mistake sometimes of reversing the plug wire order and it will run, but be rough and have no power. if it isn't that, pull the plugs again - and do a cylinder pressure test. good luck!

 

I mentioned I cleaned the wires because sometimes you can pull apart the ends when doing so. I pulled all of the wires back off and I checked the resistance in each wire. They all had a range of 3.5K Ohms to 5K Ohms depending on the length, which was the same (as I can best remember) resistance when I checked the wires a year ago. I don't think it's the wires.

The Check Engine finally came on so I pulled the codes. One code was random misfire in multiple cylinders and the other was misfire in #3 cylinder.

 

is the firing order correct 18436572

 

Forgot to mention that it's the V6, so firing order is 165432. Double checked the firing order tonight and it's OK. Pulled #3 plug wire and the engine ran the same as with it was attached to the plug. Hooked the plug wire to an extra spark plug and grounded the base and it got good clean blue spark. Did the same with #1 for comparision and the spark looked the same.

So I have spark in that cylinder, so it must be a fuel problem, possible vacuume leak in that cylinder, or maybe even coolant is leaking into that cylinder?!?!?. I'll plull the plug tomorrow when the engine is cold and see what it looks like.

 

Since I pulled all of the injectors out, maybe I boogered up #3 somehow. How do I test just that injector? Should I pull the whole fuel rail off with the injectors attached and crank the engine to see what the spray pattern looks like? Besides the huge fire hazard that poses, should I be able to see anything helpful?

 

ive done it that way before just put cardboard or something under the injectors to see if u r getting fuel and less chance of fire

 

Before I pulled spark plugs, replaced wires, moved coil wire, etc.. I decided to run some SeaFoam down the throttle body and add to the gas tank. I decided to run the SeaFoam 1st, then chase it down with some water from a spray bottle. The water turns to steam in the combustion chamber and helps knock off carbon deposits. If you don't believe me, heat up some kind of junk metal part that is greasy and hit it with some water. The grease will fly right off. You want to make sure to spray water carefully at a high idle ( I did at about 2200 rpm) and listen to the engine. It should run a little rough but not horribly rough and make knocking sounds. YOU DO NO WANT TO ADD LOTS OF WATER AT ONE TIME OR YOU MIGHT HYDRAULIC A PISTON. Water is NOT compressible and you will damage a piston or bend a rod if you put too much water in. You will also want to chase the water with carb/throttle body cleaner just to make sure all traces of water are gone so as to not corrode any air passeges in the throttle body/carb.

After the SeaFoam and water cleaning, it idles smooth and no missing. I hope this was the fix!

 

Well, the truck is running better, but still not quite right. After doing more research, my guess is that the SeaFoam cleaned up the fuel injectors a little, but I'm betting that they are the problem of the rough idle and missing at light load when crusing. I pulled the injectors out and sent them off to be professionally cleaned. Hope this is the fix! My guess is that I dislodged some junk into them when I removed them to change the intake gaskets.

I'll post another update when the injectors come back.

 

Injectors came back. Most flowed pretty well for the milage except one was in "fair" condition. Guess what? not the problem. It still runs a little rough at idle, and a light throttle when crusing. I did get a new code that indicates the crank position sensor and/or cam position sensor is not getting a consistent signal. I pulled the cap off and noticed my brand new (made in China crap!) cap had a probelm. The rotor button was cracked and a piece fell off! I went out and bought a new NAPA cap/rotor. Same problem. I double checked the cam position sensor inder the dist cap, and it seems fine. I'm gonna try the distributor index fix to see if the dist is not indexed correctly. Maybe I moved it accidentally when working on everything. I'm once again avoiding replacing a $100 part (crank pos sensor) until I try out other things. Ugggh. I'm begining to hate this truck.