Car:2000 Mustang GT 4.6 liter

mods: k&n ntake, 4.10 gear ratio. and flowmaster exhaust system

problem? When i first start my car (after i let the engine warm up) and i try to redline the car goes all the way to 6k without any problem, but after about 20 minutes of driving if i try to redline the car LAGS alot starting around 4k. Then i turn the car off and back on, it doesnt lag for the next ten minutes but after a while it will start to lag again. I got a oil change a week ago with synth. Everything else seems fine i just cant figure out why it lags, this has been happening since the begginning of summer. The lag comes and goes.Can anyone help me or does anyone know whats wrong with this car?

 

Why the fuck are you trying to hit redline as soon as you start the car?

No wonder it doesn't run right anymore...

 

Did you re-program the computer for the 4.10s?

 

redlineing in idle is a big no-no.

 

NOO MAN OF COURSE I LET THE ENGINE WARM UP, I let the stupid car sit in the drive way for atleast 15 minutes before i start driving and still i hit the same problem

 

no sir i did not reprogram computer, would that help

 

sounds like your fuel pressure is falling off

 

Is it throwing a CEL? I'm figuring you don't know whether you're hitting a rich spot in your fuel curve, right? Are you kicking up black smoke when you hit lag? When you put your exhaust system on did you put all the O2's back? I'm not a Mustang girl so I don't know how many your car has but leaving one off unresistored or having one go bad will seriously affect your fuel...but that's usually across the board and not rpm specific. Also, how do your plugs look?

 

Why are you doing that? Probably not related to your problem, but 1) idling puts heat in the water jackets but not throughout the block. 2) it's doing nothing to warm up your trans and diff. 3) it's unnecessarily putting a lot of condensation in your oil and cats.

 

i rarely drive it maybe once a week but i let it sit for a while when i start it