My 92 oldsmobile 88 royale when i go down a hill or anything when the car is cold such as within the first 3 or 4 minutes of driving when i slow down it jerks and hesitates and most of the time stalls out. now i ran the codes and all i get is a 66 so i dont think thats related plus my belt is routed w/o the a/c anyways. also when i pull off the oil cap (which the nub on the valve cover is stripped off) it does the same thing jerks like crazy like its going to die and sometimes does.

btw new maf new fuel filter new plugs and wires new pcv valve new coil packs all replaced within the last 5000 miles
any ideas??

thanks

yea no vaccum leak cleaned out throttle body still doing hte same thing there is a sensor right under neeth the throttle body no clue what it does but could that be it?

When you say that the engine wants to stall when you expose the crankase to the atmosphere by opening the oil cap, it makes me wonder if there isn't something wrong with the PCV valve or gaskets. It is cheap and easy to change and can affect the engine vacuum. Like jr's3800 said, it really does sound like a vacuum leak.

The sensor underneath the throttle body is probably the throttle position sensor; it will cause problems if bad. You can run a cheap check by unplugging the TPS and connecting an ohm meter across the output terminals. With the engine off, open the throttle by hand to see if the resistance changes smoothly throughout the range of throttle movement. An analog meter works best for that check.

I think I've heard this symptom before.

Is it possible there are two o-rings in the PCV now. Take it out and check again. I believe that'* what someone found when the car took in too much air when the filler was open to the atmosphere. Seal it off some and the bad PCV seal is mitigated.