That's what it reminds me off anyway, a lopey old cam.

It's worse when it's a cold start but it's always there to some extent.

Here's what I have done in the past month. Intake manifold was fixed 3 months ago.
-coil
-cap
-rotor
-PCM from Solo
-IAC
-TPS
-Crank Postion sensor
- Cam position sensor
- gutted stock cat

The rough idle started about 2 months ago. At that time I did the sparkplugs and it seemed to run better for about a week.

Then about a month ago the truck just died. It ended up being the PCM. When I finally got it fired back up there was a pretty severe lifter noise from the drivers side head close to the firewall. I ran some motor flush through it and changed the oil, added a can of Restore and let it sit. I had a feeling that the cat might be plugged so I didn't want to drive it until I changed it. I ordered a Flowmaster cat from an online place...3 weeks later I told him to cancel that order and I gutted the cat. I've been driving the truck all of this week and there's been no change in the idle quality.

I threw a set of 24lb Ford Mustang injectors on it thinking that maybe one of the stockers was dying since the truck has 160K on it.

There is an exhaust leak on the drivers side as well which I think is at the block/manifold connection. I have a set of gaskets that I'll be install this weekend.

Is it possible that I have a bad lifter that is slow to pump up and even once it's pumped up is still not all the way?
Oil pressure is at like 40psi at idle and 60 psi rolling down the highway.

Could the exhaust leak be the culprit?

Oxygen sensors? They're still the stock ones as far as I know.

any help, suggestions, offers to help push it off a cliff would be greatly appreciated.

Jeff

 

Does it do the rough idle thing as soon as you start it up? Or after it has been running a couple minutes?

What's fuel pressure look like?

Compression test?

How did the plugs look?

 

Starts immediately at startup, actually settles down some after a few minutes.

Fuel pressure is at 45psi

Plugs are really clean. Just checked them again this week since I've been driving it to work (30miles one way).

 

Fuel pressure is a touch low, but, shouldn't be enough to make a difference..... however, the fact that it gets better after a few minutes..... that is when the PCM starts paying attention to the O2 sensor.... so, maybe a lean burn miss?

Were all your plugs a nice uniform tan color? (they should be...)

 

Yep, all plugs were a real nice tan color. That's what makes this so frustrating, other than pouring money into the truck. All the logical things that I can think of that would cause this are not the fixes.

 

Maybe it's time for a compression test.... (dry/then wet.)

 

If your 02 sensors are original with 160,000 miles on them, then there way past due for needing to be replaced. The 02 sensors should be replaced every 70,000 - 80,000 miles.

 

Tried to do a compression test yesterday while I was installing exhaust manifold gaskets but my test guage is not holding the pressure.
Only did the drivers side of the engine dry since it was a pain to try to crank it and watch the gauge.
1- 120psi
3- 100psi
5- 130psi
7- 150psi

Naturally they're just what I could see the needle on the gauge bouncing to on the compression stroke.

I think since the lifters are about $100 a set I might order a set and see if they fix the issue since the noise I've heard since I bought the truck was not the manifolds leaking as I found out yesterday. What a waste of a day even though I could see that the manifolds were leaking some.

 

Hhhhmmm..... Think I would pick up a new gauge, and rerun that test. By those numbers, you are out of spec. (all cylinder over 100 PSI, and within about 10% highest to lowest.)