Fuel issue I have a 2002 grand prix. Lately when I drive it I lose acceration going up hills when I hit the gas pedal the RPM goes up and I still lose power. Today when I came home I slowed down on to the road and it died I waited several minutes and got it to start. As long as I had my foot on the gas it was ok, once I let up and slowed down it died again? I am assuming a fuel problem, the mass air flow was replaced a year or so ago. Do you think the fuel filter or pump? Thanks Susan

Manual or automatic transmission

Look on top of the engine near the firewall and close to the vacuum brake booster. There is a vacuum hose that collapses under engine load.
Remove and change the hose.
You can test it by doing a STALL TEST.
hold brake pedal and raise the engine RPM(by someone else) enough to produce your trouble and look at the hose above mention then you will see.
***, PAY ATTENTION NOT TO BE IN FRONT OF THE VEHICLE***.

so the throttle fails, in Park too? or neutral or in drive.
we need to know all facts here.
the throttle adds air the EFI measures that and adds fuel.
then RPM rises, to 3000 rpm easy in park.
does it do that?
then fail to make power in drive.? power is in move car?
check fuses first.
then scan it. using any scan tool works on all USA 1998 and canada. cars.

or "then it starts to go"

my guess now is ,that car drives ok, but has a small hesitation
and has full power up any hill wide open throttle and the transmission does not slip.?
is that it?
that can be a bad TPS sensor. (hesitates then catches up)

what is the delay time, from ignoring right foot to go.
1sec, 1 minute, what?

fuel gauge sender unit faulty, or bad connections to it or faulty fuel gauge as a last resort.

you could have a bad motor mount.

You have to separate transmission slippage, which
there is no fix for,from engine drivability issues

Then give us more to go on

i would change fuel filter and if that does not do it, have the fuel system pressure checked. fuel pump may be going bad and loosing pressure. let us know what happens after this. thank you

shuttering going up hill usually means fuel filter needs replacement

This can be Caused by Both the Fuel Pump and the Fuel Filter. If you have not Changed the Fuel Filter in a While, Try that First and see if it Helps Before going to the Fuel Pump. It is Easier and Cheaper that the Fuel Pump to Replace. Please Rate my Response, I need all the Help That I can Get! Thanks!

I have the same car and i had the same problems
I did the same stuffs you did to try and figure it out
The answer, my friend is
REPLACE THE CATALYTIC CONVERTER
My mechanic replaced the catalytic converter and WOW, it runs like a brand new car
The car was getting dangerous to drive and now you touch the gas pedal and it goes
good luck