Weird Problem when first put into Reverse

Hey everyone. I've posted here before about numerous topics for my 89 Riviera.....recently a new problem developed. I don't drive my car much at all, and Im in the process of restoration. However, two weeks ago when I started her up, I put her into Reverse and the engine started sputtering, and on the gauge screen the rpms dropped to about 450-500, and the car sounded like it was going to stall out. Suddenly, the revs picked back up, and it went up to about 1500-1700 rpms. I know normally, that when first started, its on automatic choke and rpms are stable at around 1100 rpms. I'm totally lost why my car started doing this. If I shut it off, restart it, put it into reverse again, then it doesnt sputter and act like it is going to stall. Any ideas? The car hasnt thrown any codes at all, but I know it isnt supposed to do this!!!

I would think that the Mass Air Flow sensor is going bad. Next time it happens try tapping it with the handle of a screwdriver. If it straightens out that should be your problem.

The next thing you should clean is the Idle Air Control. If you go to Ronnies site there are pictures and directions to show how to do this.

It may have something to do with the torque converter draining down when the car sits for an extended period.

Not sure why that would affect the engine RPM unless the ECM was sensing little or no resistance at transmission.

IAC

Thanks padgett.....when I get a chance I will clean the IAC....I doubt its the TCC as others suggested....the car only sits for maybe 3 days or so at a time and I start her up.

Click here for Padgett's instructions on cleaning the IAC.

Put a rag under the IAC to catch a screw if you happen to drop one while removing the IAC.

Will do Ronnie.....don't need screws and bolts causing any other problems!