Does it studder? I had a injector that wasn't seated all the way (my bad) when I installed my magnusen nose and it would only studder when accelerating, didn't even get a check engine light. But I re-seated the injector and all was well. Otherwise its prolly the normal wires/plugs ordeal. I am sure you got the right belt for your 3.4 and it ain't slippin. Had some nasty slip with a 3.0 pulley once, that made it hesitate too.
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1999 Forest Green GTP, 3.4 pulley, Magnusen snout, Thrasher CAI, Mod PCM, Eibach Springs, Koni struts, Pods Tranny Temp/Boost, Optima Redtop Battery, Tranny Cooler, Borla Cat Back, Ubend removed, Blazertech 3200's,