A few things first ,the car started this bump/shuttering problem awhile back its a hit and miss thing, it's a 96 gt,so i replaced the plugs w/ autolite 742 ,new 9mm frpp,2 new coil packs,new fuel filter,i have a 2003 throttle body & plenum,mac cai,march underdrive pullies,new tps,idle air control valve,new altenator ,new water pump,new battery,3.55 gears,it has a aode,now i have not checked the fuel pressure because the car runs so great,no check engine light on what so ever,no problem with idleing ,but it does it slightly without the a/c on,but turn on the a/c and it bucks once in awhile very hard and the rpm's drop, I'm begining to think that it might be my torque converter,or something in the trans,or a computer issue,its not a blown head gasket either beacause i'm not losing any coolant,any suggestions would be highly appreciated!!!