i have a tbi 350 and it fluctuates at idle and it bucks after about 2500. it only used to do this durring the summertime when i had the air conditioning on. i have replaced the plugs, cap, wires, and the rotor. any ideas as to what the problem may be? does it have anything to do with the A/C system?

 

That's going to be pretty hard to trousleshoot seeing how they didn't put a TBI 350 in a 3rd gen.
I'm assuming it's a transplant or a 350 put underneath a 305 TBI system.
I'd change the TPS and calibrate it.