91-Z28-L98 - thanks a lot !! i will probably have someone help me check the timing so i can learn also. Well i don't know if this would tell me if it was loose or not, but when i took it to a shop right after i bought the car they told it was the coil. So i had them put a new one in and it still ran like crap. But the thing that made them think the coil was doing it was that it was just laying on my motor basically, like it wasn't bolted down or anything. So what i am trying to say is that since that was loose that maybe the distributor is loose too? Will it still idle fine thought if the timing is off? Cause it idles at a consistant 750 or so. Thanks for the help!! sorry to intrude on the thread but i didn't want to start a whole new one on this subject.

-lance

 

Sounds like a case of water in the fuel tank: worse on acceleration, gets better when adding solvents to fuel, shuddering...
This happened to me before, really bad after a quick stop, or going up a steep hill. I drained almost 2-quarts of water out of my fuel tank.
Some garages can siphon pump out the contaminated fuel, if that turns out to be the problem...hope this helps..

 

At first I thought it was water/contaminants in the tank as well, but then I ran the tank down to empty and refilled with no change. Eventually, contaminants would work their way out I would think.

 

If you have a EGR code, logic tells you to start there. Get a diagnostic sheet for the code/codes you have from a local dealer, they'll run you a copy. Once you rule out your ECM codes, then start diagnosing the mechanical things.

 

I ran my car so empty it wouldn't stay running, but it still never removed the 2 quarts of water I found when I actually dropped the tank...

 

I checked the fuel pressure today. My readings are approx:

22 @ fuel line prime/no ignition
32 @ idle
26 @ WOT

I would assume this is the reason my car idles decent but runs like crap when changing throttle. 32 psi is a little low for idle, causing a noticable but not serious roughness. However, the pressure DROPS when throttle is increased, I'm guessing because the supply cannot keep up with the demand.

Also, I've noted that the fuel pump sounds normal (high pitch whine) when priming from 0 psi but when there is already pressure on the line, it sounds sick. I have listened to fuel pumps that I KNOW are bad and they sound lower pitched than normal, but my fuel pump sounds like it has bronchitis or something. The lack of pressure may be because the pump is bad, or maybe because the screen is clogged, but replacing the pump should fix the problem. I'll empty the tank and refill with good gas when I drop it, hopefully to remove all reminants of impurities. I'll post results when I'm through.

 

I had one of my vehicles to a dealer for :stalling, shuddering etc.
They said first,"It just needs a major tune up".(years ago)So, I agreed to let them do it.($130)...no change.
Then they said, "Low fuel pressure, it needs a fuel pump." So, I let them do that too.($260)..no real change.
So, they did some more checking and found a hole rusted on the top side of my fuel fill pipe...and gues what, Water in the gas tank! And had the nerve to try to charge me another $165 to steam clean and refuel it...I refused, based on how it was the water ALL ALONG.
Anyways, water can cause low fuel pressure and shuddering and stalling. Some garages have the siphoning equipment to remove the fuel+water without dropping the tank....it might be worth checking into before doing major work removing it, unless you just want to add a 255LPH pump, this would be a good time. I noticed a tenth improvement when I installed mine, especially could tell on top end!