94 toyota, fuel or air intake valve

hey...ive been here before and you guys are real helpful. my car is teetering between problems and i thingk maybe psychotic. Putting gas to the floor and loose power. I was on the 405 doing like 30mph and it was just dronining like brrrrrrr....really low grade. i let up on gas and it would slowly come back...then spurt....a burst and i could shift up...but oh wait...brrrrr....its going down agian.....etc. finally got home and just playing around on gas pedal...its not doing it anymore. I was told I might have problem with air intake valve...but that was when the car was just dying. My freind fixed that by adjusting the idle. i had a bad mechanic mess things up i think. so the car stopped dying and i thought i was ok...but then this sputtering...low grade thing started happening again...ugh....anyone? oh 94 toyota truck...like a tacoma.