I have a 98 Monte Carlo 3.1L w/100K miles. The car sputters while driving at constant speeds. Problem begins around 30 mph.

I have replaced the wires, plugs, Air filter, fuel filter, cleaned injectors, throttle body.

http://www.automotiveforums.com/vbulletin/showthread.php?t=644244

After reading this thread, I am going to replace the Vapor canister filter.
Where is this on the car? Near the fuel tank, or at the engine?


Thanks much.

It is back by the fuel tank, drivers side of the car.

AC-Delco part# 215-176 (GM# 17113327). The other part numbers are not totally accurate in that thread. The one part number (pt250) is for the replacement wiring pigtail that goes to the purge solenoid under the hood, not the tank vent solenoid.

Since your car is a 3.1, I have a question. Are you mysteriously losing coolant and/or have you noticed coolant in the oil? Your symptoms are classic intake manifiold gasket failure. It starts out as a misfire due to coolant being drawn into the engine and can prgress into your oil being overfull/murky looking due to coolant contamination.

I am not loosing Coolant, Oil is good also. Thanks for the response.

I also replaced the PCV, and the rubber elbow boot (split up the side).

I did have my other car (Malibu) head gasket replaced at the shop I recently took the Monte Carlo to.

I had them look into the head gasket (thinking the same), they said it appears to be fine.

In your opinion, driving the car with the intake leaking air only, am I damaging the car? I will not be able to get the car into the shop again for the next 3 weeks.

Well, I spoke to soon on the intake gasket leaking. Yesterday, I noticed a puddle on the floor. It was antifreeze. Although I have not lost fluid in the past. It had to start at sometime. So I took it in the shop this morning. They now confirmed the gasket issue. 2 - 3 weeks ago, they claimed was good.

nobody is perfect I guess. I'll post once the repair is complete with the results.

Thanks again.