98 4.6 Poor Throttle Response. Loss Of Power 3500 - 4800 rpm range

[98gt46]

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 ?

 

[Yellow2002GT]

Sounds like a fuel problem....clean your injectors and change your fuel filter! If that doesn't work then check on the electrical side! I.E. coils, wires.....

"ED"

 

[98gt46]

changed fuel pump and filter , cleaned injectors. new plugs, wires, o2 sensors and ignition coils. i still havent fixed it. now im just too broke to throw any more parts at it. altho one time it did go threw second gear all the way to 6000 rpm only missed once or twice , but only the one time. aside from that the miss seems to be getting worse. today it didnt want to start . junk computer ? whats a new one cost ? can i get a new computer thats already set up for premium gas and has the 120 mph. speed limiter removed? more set up for performance not fuel economy. ???????????????????

 

[jcint]

my 96 gt got a real boost when i cleaned the MAF. http://www.bullittarchive.com/1007.htm

 

[sgarlic]

You gapped the plugs before you installed them right?

 

[tomustang]

you know even if you IAC went bad, cleaning it won't do anything

 

[Mossberg]

Seafoam that bitch!!!