hello I have a 2000 monte carlo ss with a 3.8 my problem is when I start the car it idels fine if I give it gas it stall out. if I try start it agine it fights me to start, when I get it to start and take it to 2000 rmps and hold it, it runs fine when I let off it dies agine. new MAF new idel control sensor new intake gaskets plenum gaskets new battery. Im lost

 

Sounds to me like its the Throttle position sensor
Id replace it! theres no real way to "clean it"....So, Id take it off and see what it looks like...
Hope this helps!

 

well i took the throttle sensor, idle sensor and mass air sensor off my 02 bonneville and put them on the monte same issue. The issue starts when the car starts to get worm.

 

First, I will ask, any check engine codes? Has anyone scanned the computer for any codes (even if the light is not on, it may have code data that a good scan tool can read).

I think you have one of two issues. Either a bad MAF or a seriously messed up cat (I'm a little guessing at the cat as GM had a ton of bad ones in 2000 and 2001, so bad they extended the warranty on the cat, but it's now past that).

Try this first:
- Car off, disconnect the MAF. Start the car. In theory, since you borrowed the MAF from a known good car, this test should fail. But if it runs fine, you have a MAF related issue.

As for the cat, I only know two ways to "test" for it (not sure what the true diagnostic is). The ways I know:
- Unbolt the down pipe from the rear manifold (I've done this from under the car when I changed my cat, need a LONG extension) and make sure the outlet of the rear manifold is exposed.
OR
- Remove the upstream O2 sensor. Leave the hold for the O2 wide open (gives exhaust another "small" exist.

- Either method, start the car, any change? If so, your exhaust is plugged.

AH, wait, I'm missing ONE more. While the car is idling, look under it at the cat. If ay ANY point, the cat glows red, you found the culprit, a failed cat.

 

thought the same so I cut it off! but did not help and aslo tryed unpluging each sensor. And no on the scan tool cant get the car to a shop. I do have a check engine also abs and traction light.

 

I guess jason would know better than I....

But are you sure the Bonneville is interchangeable with your MonteCarlo? your is a 2000 and the Bonnies a 2002?

 

between the two cars most of the sensors are the same part number.

 

Vaccum leak maybe? Also check fuel pressure at the fuel rail with a gauge.