Saturn Repair: Saturn Stalling, brand new car, degree day

Question
I have a 2001 SL2 Saturn. Last summer at about 36,000 miles I started having my 1st ever problems.
I would be sitting at a Light when I would feel the power giving out. And/or when I started it, it felt Sluggish. I would be creeping down the road and then it would catch on and be fine. Then there were a few times when after being out and about it wouldn't start. It would turn over till I let go of the key and then it would die out. One of the times a Tow Truck was called and he gave me a Jump and said I needed a new battery. I took it right away to the mechanic. They ran a test on the battery and found it to work like new. They also ran other tests on my Car and said my Car acted like a brand new Car. I took it home Unfixed. Then I got a Tune-up on it. And for the Fall and Winter till May came (I live in Phoenix). It worked like a champ.

I first noticed this problem again when I went to turn on the Air Conditioner. It was immediate that the car became Sluggish. I thought for sure it would stall out. I turned off the Air Conditioner and soon after the car was fine.
Then just last week, on a 100 degree day (while not using the Air Conditioner), I was out and about. Had just made my 4th stop and when I went to start my Car it died as soon as I let go of the key.
I took off the emergency break, put my foot on the brake and gas and jammed it into gear. It went but oh so slow. I wasn't sure if it would catch or not but it did. All the way home it threatened to stall at lights.
I haven't driven the car for 3 days now, but I got into it this morning and it started right up with no sign if problems.
It seems to me I have problems when the weather is Hot, and when I turn the Air on.

I have been to various Sites here online reading people's Saturn Woes. Many of them talk something similar to mine and they all say that their problem has caused them hundred of dollars trying to figure out what it might be, to no avail. It's not very encouraging. LOL

Could you give me any ideas as to what my problem might be?
Michelle

Answer
Michelle,
 I'd bet you dollars to doughnuts that your problem is caused by a faulty fuel pump.  I've replaced a hundred of these ('98-'02 S-Series fuel pumps) if I've replaced one, for this exact condition.  You will only notice the sluggish-ness on hot days.  If you will have the fuel pump replaced I promise that you will no longer have these problems.  Your fuel pump has a little plunger inside of it (the actual part that pumps the fuel). On most of these Saturns, on a hot day, the plunger will expand with the heat.  The sleve that this plunger rides in does not expand.  Hence, you get a plunger that will not move freely inside its sleve.  Hope this helps

Chris