hesitation after 20 min

Hello people,

I drive a 2000 pontiac grand am gt. It has 156,000 km on it.

My problem: Car hesitates between 10 - 20 minutes.
(this seemed to start after my overheating problem)

Fixes: Thermostat (for overheating), didn't fix
changed lower gasket (overheating fixed- yes)

Hesitation attempted fixes: tune up (didn't work)
temp sensor bypass (didn't work)
map sensor (didn't work)
fuel pressure: 50 - 55, between 10-20 min dropped to @ 47
all prelimenary diagnostics: failed

note: car hesitated between 10-20 kms,

all codes cleared by mechanic, I started getting 120-180 kms before it would start hesitating.

Dealer suggested fuel pump is overheating, i don't understand why I would consistantly get 10-20 kms with minor hesitation and after the mechanic cleared the codes, I started getting 120-180 kms then it started getting worse again. I had a fuel pump put in at 98,000 kms, that was just about 2 years ago. The mechanics I talked to never had a over heating pump fail like the way mine is failing. Someone out there must have had the same problem as me.

I have been looking through this forum for the past month or so now and I noticed that some people had similar trouble but most of it has already been ruled out already.

Your help or ideas will be greatly apprieciated.

catalytic converter

I been told by almost every exhaust shop around here that the catylitic converters dont usually start having troubles till 10 years , but could explain the hesitation. I ran my car for a year with cat removed and it set off the check engine light for a year. Finally I purchased a 02 simulator to stop the post cat sensor from detecting it missing. Well it took my car a couple weeks to Learn that the new signal took over and when it did it was like driving a new car , no back sputter , no rough idles , no hesitation low or high end and sounded better outside as well. The pc's are so picky on these new grand ams , for example the car will run like crap if the gas cap isnt on right. Never played with such a touchy car before.

Thank you for a quick reply. I have 2 questions.

1. what are the symptoms of a failing catalytic converter?

2. What can I do to try test it if it is failing?

Once again, thank you for your info.

dude you removed your cat? how do you get away with that? hollowed it out or what?

Is it a Heated O2 Sensor or Single-wire? Would make sense if it was a single wire.

my 2000 ga gets doggin it when it gets hot too , the engine gets so hot it heats up the air going in thus making less hp. Thats what causes mine to lull also I think if the catylitic converter was malfunctioning it could throw a service engine soon light and then it really dogs out cus its getting improper signals and tries to lean out the gas. You could replace the cat or buy an o2 simulator , but if the cat is gunked up the o2 simulator isnt going to help. I have my factory cat still but its in storage to be sold on E-bay soon , you could have first dibs for 30 bucks plus shipping no haggling.

Has anyone had an overheating fuel pump?