My Tacoma keeps stalling

I have a 96 Tacoma 2wd that I bought a couple months ago and about 3 times now while driving it has acted like it was going to die, and it does it 3 or 4 times and then runs fine. I had the spark plugs and the fuel filter changed but four days later it did it again. Someone suggested that it's probably the fuel pump so I actually bought one and a friend was going to put it in but then got called back to work and doesn't have the time sooo... I took it in to a mechanic and they did a bunch of diagnostics on it and $75 later it's still not fixed. I was crossing my fingers that maybe the problem was fixed since I not only had the fuel filter changed I also stuck some injector cleaner in it.
The mechanic said if it were the fuel pump it would be stalling all the time, not just once in a while so he checked all the electrical, the ignition coil, everything he could think of and came up with nothing. He drove it several times and of coarse it never acted up.
I actually just shipped the fuel pump back two days ago because I was able to return it if it was with in 30 days and guess what, I started my pickup and it idled for about a minute then sputtered several times acted like it was going to die then reved back up and finally did die. I thought since it was only about 20 degrees out and had been sitting for days it was probably just cold so I started it again but even after the temp gauge was up to normal it did the same thing, it almost dies but then catches itself like it revs back up over and over again and then finally dies. I drove it down our driveway and had to give it more gas to keep it from dieing.
Any suggestions? Is there any chance a leak in a vac hose would cause this with out a check engine light coming on as there never has been a check engine light. Any suggestions would be greatly appreciated.