Surging acceleration on 2001 Pontaic Grand Prix

108-K miles, 3.8 L 4-spd auto.

Takes off from the line and downshifts normally, but when you want to accelerate graudally, the engine wants to surge or “pulse”. You can see the tach needle bouncing up and down while it’s happening.

This takes place with the engine running between 2 and 3-K rpm. It won’t snap out of it unless I mash the accelerator and force it to downshift.

My mechanic replaced the mass air sensor after the computer came up with a corresponding code suggesting that might be the culprit. But about a month and $200 later, the same problem.

I don;t believe its an transmission issue being there’s no other shfiting troubles and telltale sounds. Any other Grand Prix of GM owners have a similar problem, and if so, what was the remedy? Thanks.

A loose or broken throttle position sensor can cause surging. This MAY be the fault.

The fuel filter could be the culprit. Put a clean one on.
Your mechanic could test the fuel pressure with the engine under load — simulating the condition where the problem occurs.

UPDATE: Replaced the fuel filter…11-K on the old one so it was about due anyways…the susequent test drive showed normal acceleration. The missus took it on the freeway today, says it seems to run better and didn’t notice any surging. Hopefully, that did the trick, but I’ll keep an eye on it. I like simple solutions.

Thanks to all for your helpful tips! Hope to return the favor in the future!