Hey guys, my freind has a 91 firebird with a 305 tbi motor in it and it just started having this problem where you are driving and u are at say 2200 rpm, the car will just bog and go to liek 600rpm and then kick back up to normal, and sometimes idle at 1200. Now we thought it was the fuel pump on its way out but it pulls constant pressure even when he has the problem.What could it be on the tbi?? I have an extra tbi distributer, should we try swapin them out or could that not be the problem??