1991 Toyota Celica Engine shuts off on hot days

Engine Performance problem
1991 Toyota Celica 4 cyl Automatic 158000 miles

On July 4th, 2008, while driving on the freeway my EFI fuse blew out. I am not mechanically inclined so I had it towed, not realizing it was a quick fix. The fuse was the right number (15), but it blew out a few times afterwards as well. It seems to do it only during summer/early fall when the days are hot. It happened mostly as I was stopping or slowing down. Than it got to the point where it wasn't the fuse, the engine would just shut off. I would wait about 15 - 25 minutes and the engine would turn back on and I would be fine for a while, unless it was a very hot day than I could only get about another 2 miles before it would break down again. It was never the fuse anymore, but just my engine shutting off. I could turn it over but it won't start until it cooled off I'm guessing. Exact same thing with it would shut off as I was slowing down or stopped. Recently for the first time in well over a year the fuse for the EFI blew out again, at the time I had a very heavy load (3 heavy-set people) in my car and was driving it for a while when the fuse blew out and was slowing down. I have had either a new coil or relay put in, I don't remember. Also new spark plugs. The 3 different mechanics I have taken it to have said they needed it to break down on them for them to see what it was wrong, the days were cold and it did not break down on them.

Couple of notes:

1)Car shakes alot when idle, seems like it shakes as I'm braking as well. Get's even more shakey when I turn on the AC

2)My pedal needs to be pressed down a little harder to accelerate, it is kind of sticky (Don't know if that matters at all)

3) First it was EFI fuse blowing out, than engine just shut off, recently fuse did blow out. Days are starting to get hot here in California, so I'm expecting some more break downs. Breaks down faster and more often the hotter the day is. Breaks down when slowing down or stopped.

4) Amount of gas in car has seemed irrelevant because it has broken down on all types of levels of gas I've had in my car.

5) I believe the last mechanic I took it to said that the computer didn't show any errors. He gave me some spark plug tester, but I can only use if there is another person. He told me when my car breaks down to stick into the spark plug area and push on the gas pedal while my car is on "ON". If it shows a spark than he said it's probably my distributer, and if there is no spark that it is probably my fuel pump.

6) Recently I have heard it could my something about an O2 sensor or my thermostat. I don't know anything cars though.

Please help! I would like to be able to drive somewhere 100 miles away on a hot summer day without any problems.