astro driving me to drinking!

please someone help!.....1994 astro all wheel drive,240000 kilometers on it,4.3 vortec...heres the deal....she has started running rough(but starts right on the money)and ildes rough too.changed the plugs,rotor ,cap, fuel filter,wires,but stills runs rough.it started doing this intermittantly,then after a few days really started doing it all the time...bought a code reader,no codes detected...no service engine soon light on either,but i know it works cause it lights up at start-up.whats the matter with this van?...i cant bare to get rid of it,its so pretty and nice to drive.any help would be a blessing and id appreciate it muchly.

8th digit of the VIN please....

If VIN=Z, I guess a bad TBI to intake manifold gasket.

What do I win?

i would check the TBI gasket as mentioned....first...you can spray brake fluid at the base during idle to see if you get any changes
then check the fuel pressure....possibly a weak fuel pump
next would be catalytic converter

let us know

carb cleaner - not brake fluid please...

brake fluid will make a big mess

carb cleaner will evaporate..

my '94 "w" engine astro will get like that periodically- and I can tell it has a piece of carbon stuck in the egr valve seat- I pull out my scan tool and check egr pintle position- it is usually 25-50% when the requested position is 0%-- Then I exercise the egr valve to 100%- while holding up the rpms to keep it running- and the chip gets blown out of the seat- and is able to seal properly. I know it is a chip because the first 2 or so times this happened- I pulled out the egr valve and saw it- then cleaned it , then it was okay- but the scan tool output option is much easier and faster. But mine usually set the service engine soon light- good old code 35 or is it 32? I forget......

have seen several of these where the distributor magnet cracks at the pick-up coil. will start fine because of EST. Should be able to see with cap off. Need to replace dist. shaft if this is the case.

Poking around internet because I think I have EGR symptoms too but haven't gotten my hands dirty.

From http://www.asashop.org/autoinc/dec97/egr.htm


"Repeat failure is a common problem. You can recommend a top engine clean to the customer and attempt to clean loose carbon from the upper intake. GM has noted the problem and come up with a software update for the PCM. Essentially, what the update does is periodically command the EGR to 100 percent opening to prevent or flush out carbon chunks. The new prom numbers were in a "special policy" procedure bulletin and not a regular TSB. The special policy number is 96067(A). It refers to '92-'94 S/T, M/L and C trucks with the 4.3 V6 engine and linear EGR valve. The bulletin number is 67-65-38. It refers to '95 C, S/T and M/L trucks with the 4.3 V6 engine and linear EGR valve."

Interesting. If you do end up replacing the EGR or even taking it off to clean in there, replace the gasket with the type with a screen built it. It will save you troubles down the road.

thanx to all that responded to my problem,it was the egr after all,and was replaced .now shes running like a scared rabbit(the animal,not the car)...you people really know your stuff..,indebted to a.f.,smellywetdog