I am writing in desperation, I too have sick 94 with the same symptoms as many others.

long crank before start (hot or cold, used to be hot only, but now on the morning start too) - light throttle opening or feathering helps start it quicker

stumbles and bucks under 2k (can't use 6th at 65-70, just bucks and shakes) - maybe 1800 to be more exact

pulls hard and smooth above 2k

fuel pressure jumps and holds to low thirties when key on, 42 or so when idle with vac tube off. varies with rpm with it on. pressure drops from 30+ to 20 over 10 minutes after shutdown. Takes a few hours (overnight) and it is back to zero

egr was stuck hard - replaced (old one sounds like its full of sand)
opti was toast - replaced (oil contam complete with mucho tracks)
plugs - replaced (hate to admit this but, 2 and 8 were original, .085+)
wires - replaced for first time, have check correct routing 4+ times
rebuilt throttle body - mucho oil and bad gasket in top

cat gets very hot in 10-15 minutes ( i can feel the e-brake handle heat up). used to take hour or more of stop and go to do this

I too have low oil pressure consistantly, low 20 when hot at all RPMs

fuel is getting dumped on right bank for a perceived lean condition

160,000 miles stock everything cept Centerforce DF

Sounds like a full rebuild to me, maybe the valve train is tired

Is there a relationship bewtween oil pressure and hydraulic lifter functionality?

if not, maybe injectors probs?, exhaust leak? I have checked extensively for vac leak and vac is very strong (forgot reading but can check qucikly if you want to know)

O2s are original but that doesnt explain same prob in OPEN loop

No codes, ever, even before everything was fixed. Everything I changed had a problem except the wires (just old)

Will swap injectors to see if lean follows as soon as I stop being so bummed about all this. When I started it acted like the typical opti prob (i've had 2 already)

Prob is I just don't see bad injectors working great at 5k (pulls great), but falling on there face below 2. But I will try.

I understand if you don't want to go down this road again. I have searched and read 10+ hours here before I signed up and I use the f-body site too. I know it is a used up topic.

Thanks if you help!
Sean

putting a recent scan into a spreadsheet, will link soon

 

You probably know all of this but:
160K miles on original O2s? They are shot.
Fuel pressure should be 41-44 psi.
Might not be a bad idea to pull the valve covers and reset the rockers after 160K.
Is the battery charging properly? Maybe it's slow to start and runs bad at low rpms because of low voltage?
Maybe its time to go up a viscosity level to raise oil pressure.

 

Thanks Bud,

O2s are definately next on the list. Won't help the long crank thing though, and I doubt it will affect the below 2k thing (happens in open loop too). Probably have the most affect on the the lean at WOT (isolate real or not) issue.

The way I read the fuel pressure requirements, 42 with zero vac, I seem ok. Pump is less than 20k, filter is brand new.

Do I adjust rockers according to the GM manual (got one) or is there a preferred method?

New battery, I was borrowing the P/Us for t-shooting until the opti was done. Bought a new GM one after that for Z.

Is that the common practice? Thicker oil? Anybody bring there oil pressure up and see the hard start/low rpm stumble problem go away? This is the correlation I am wondering about.

Clogged cat? Or does that trash high RPM performance too?

An exhaust manifold leak will not affect the way the car starts cold, right?

Thanks again, I'll start wrenching in a about an hour (wife gets home and takes over kid care )

Sean

 

Original cat at 160K? It's shot too. Maybe you can punch something through it to unclog (if it's clogged, sometimes they burn out instead of clogging)
I don't know what procedure the GM manual recommends but I assume that its the right way.
An exhaust leak should not affect starting.
I would not expect oil pressure to affect starting or performance. Low oil pressure is indicative of a worn oil pump and/or greater than optimum bearing clearances due to wear.