my 98 gt has issues it is a pretty quick car but when you hit 3500rpm it misses untill it gets to 4800 rpm then it picks right up and everything seems normal. sometimes you can hold it wide open and it wont rev up past 3500 - 4500 rpm. i was told it may be a bad o2 sensor or iac, but i cleaned my iac and nothing changed. mil hasnt come on. if it was a fuel pump you wouldnt think it would pick back up in higher rpm. iv also noticed that there is poor throttle response , more like a carb engine than a direct injected engine. iv driven other 4.6 cars and they dont lag like this. anyone have any ideas ?