27hg at idle?? is it idling high? or normal? should be 17 to 21 at idle, its almost as if your ignition timing is to high, but, you cant adjust that,i wander if the egr could have something to do with it,also how does your spark plugs look, are they all a nice tan color, are they all white? or are some white and some dark??could have a lean misfire going on possibly..

 

Idle at 650 (before plenum fix was 1200-1500,)
Plugs are white (looks just like they did when installed 400 miles ago)
No egr valve

 

White indicates you are running lean. How is your fuel pressure, and how old/what brand are your O2 sensors?

 

I don't know for sure how the fuel pressure is? I have a vacuum/fuel pressure gauge but don't have the fittings for testing fuel. The mechanic wasn't too concerned with fuel pressure...thought it was fine. I don't know the brand and age of the O2 sensors. I've only had the truck for nearly 3 years and only put about 7k miles on it.

My concern is the high vacuum reading. According to vacuum gauge charts, HIGH steady reading indicates choked/clogged air cleaner filter, stuck choke, or restricted air intake. I REALLY do NOT want to dissemble everything again to remove the manifold I'll look down the intake tomorrow and see if there's any oil in the bottom. Other than that, I'm really disheartened about having to take off the manifold AGAIN

 

OK...just for my own satisfaction, I hooked up MY vacuum gauge. Truck warmed up at idle, the vacuum gauge reads a steady 17-18 in hg. When I blip/goose the throttle real quick, the gauge goes to zero, then goes up to 21/22 in hg then back down to 17. To me, it's reading fine..at least, according to the vacuum gauge charts, it's operating like it's supposed to be.

 

haven't cleared the codes from this morning...still have P0300/0301/0308 STORED
Now have all the other cyl codes in PENDING status...

 

I bet the culprit is the cam sensor. Check it and be absolutely certain the wiring is 100% solid and that the connectors (inside) are clean.

 

Well...the only component that I haven't changed twice is the cam sensor...lol. For S&G's I'll get a new one and also a crankshaft sensor too...after that I'm giving up

 

I doubt it's the cranks sensor and, my advise, is to stop swapping parts and come up with a troubleshooting plan. Inspecting and testing each component (voltages, etc) it the only sure fire way to locate the cause.

It's been a while since I've read the start of the thread, but have you checked the coil pack and its associated connections?

I still have quite a few of the ignition system components from my '97 I'll send you for shipping. That way, you have some known good replacement parts.

Shoot me a PM if you're interested.

 

For S&Gs I just saw a truck that had misfires as well that culprit turned out to be a severely clogged cat. This truck wouldn't rev past 2k though. Not revving to 3k will still indicate clogging. I only throw this in because it's simple enough to check by trying to rev past 3k.