I have a 2002 996T that just crossed 49k miles. I've noticed over the past month or so that sometimes when I am cruising at pedal steady/part throttle (let's say 3rd or 4th gear at 40MPH+/-3) that there seem to be spots where throttle response feels wrong. If I adjust my throttle input slightly, things will feel normal again, almost as if there are sort of dead spots. I don't see codes in the Durametric, so I don't have a lot of places to start looking for the problem. I am just sort of initially guessing that either throttle position sensor or MAF would be at fault for this.

 

i don't think you're feeling the "variocam" stutter anomaly our cars exhibit, but perhaps you are. the spot i stay out of for long is just about 3k. though momentary and rpm related, it's annoying as hell

this all assumes no cracked coils/bad plugs dirty fuel filter ..and on and on....

 

If the MAF were acting up, if there was a throttle position sensor problem, there'd almost certainly be a CEL and one or more error codes.

What I believe is going on is you are driving the car, operating the engine, in such a way you are encountering the point at which the switch from high lift to low lift (VarioCam Plus) occurs.

This switch over is done at low engine RPMs (~1400) to reduce pumping losses which improves gas mileage and lowers emissions.

There is a graph in the owners manual that shows speed vs. RPM for each gear.

In 3rd/4th gear at around 40mph (+/- 3mph) the engine RPMs are about where (~1400 RPMs) the VarioCam Plus (low lift) switch over occurs.

My advice is to adjust your driving to avoid operating the engine at or below 1500 RPMs unless absolutely necessary and then only in 1st gear.

 

unplug the maf harness see if it goes away...
pressure test the car check for boost and vacuum leaks... every P car owner should do this once a year... Im guessing stock ECU
markski

 

If you've only been experiencing this for the past month, something may be slightly off. I had a similar issue and codes related to the MAF eventually popped up but it took a little while. I'd start by checking the MAF by disconnecting it like mark said and see if the symptom goes away. The PSM & ABS lights will come on when you disconnect the MAF but they will turn off after 2 drive cycles iirc once the MAF is reconnected. If it is the MAF, get some MAF cleaner spray and clean it. This solved my problem.