Pontiac Repair: 2000 Grand Prix-Sporadic Accelleration, throttle position sensor, grand prix 3

Question
My girlfriend has a 2000 Grand Prix 3.1 liter, and it will sporadically be non-
responsive at the pedal. I'll push it down to accellerate and it wont really rev
or do much of anything, If I back off, and push it again, it will accel
normally... It's hit and miss, Some days it is always ok, some days it always
screws up like this. I replaced the fuel filter for good measure, and it seemed
to do the trick for oh about a few hours then it was back to its old tricks. I
have heard it could be the throttle position sensor, and I have heard it could
be partially cloged fuel injectors. Any advice? and any kind of cost estimate
for the cleaning of the injectors?
(PS no codes come up when hooked up either)

-Peter

Answer
Hi
IF all this is happening while driving, and NOT while sitting still, I would HIGHLY suspect the Catalytic Converter.
If it happens while in park or sitting still, I would take it to a repair shop and have the data checked. The TPS should smoothly vary voltage from about 0.5V closed throttle to 4.7V WOT (wide open throttle.). Also from 0% to 100%.
Also check all cables and throtle body for binding that could be causing your problem.
This is my advice.
I Hope this helps.
Good Luck
Pawl