Ford Repair: 2000 mustang gt poor throttle response at1500-2500 rpm, cold air intake, infrared thermometer

Question
have a 2000 gt with 78000 mi. poor thottle response at low rpms, lags going around corners in 2nd, and hesitates on freeway in low rpms, no punch, feels like not getting fuel, idles at about 800 rpm. changed fuel filter, not too much gunk came out of old one, only mods are 70mm throttle body and cold air intake, thought this would help, didn't change performance. fuel injector treatment? bought car like this, just expected a little more giddy up. please help, have about 400 more miles on dealer warranty if it's serious. thanks.

Answer
Is the check engine light not on? If so, run down to you're parts store and have the codes read. It almost sounds like bad catalytic converters. A quick way to tell would be to put you're hand over the exhaust and see if there is any noticeable difference between the two sides. The real way to test is with an infrared thermometer. If there are no codes stored, have the fuel pressure tested. If it was me, I would take it to wherever the warranty is good for, and tell them the problem. You are right, when you get the motor right, it is going to have some gitty up.