Hi, have 99 mustang v6 and am wondering what could be causing this, only started happening recently, but when i go WOT when it gets to like 4000 rpms it feels just like i hit the rev limiter, the car backfires sometimes like it too, if i ease on the peddal i can get to 5000 but then if i floor it from there its like i hit a brick wall and goes to 4000 again and sputters, however when i turn the car off and restart it its completly fine for about a minute or 2 and then it starts it again, what could be causing this? I am out of town and need my car reliable to get me home.
CEL was always on from o2 sensor, today it got to th point where i couldnt drive the car lke it as misfiring and barly could move, put new plugs in it(old ones looked horrible) and now its just bucking and boggy and sputtery whenever i accelerate and wont get past 3000-4000 rpms, when i floor it, sounds just like if you turn car off WOT and keep the pedal at WOT while it revs down.
have the CEL scanned again.
if one of the guys at autozone or where ever has a half-decent scanner, see if you can find out what your fuel rail pressure (FRP) currently is.
and post a close-up pic of one of the old spark plugs.
Just took it for a drive then, if i just take my time in low rpms through all the gears it doesnt even seem like theres a thing wrong, when i go into second and get to about 50-60-70km slowly the car starts bucking and sputtering(high rpms) and if i then floor it, its just like i turned the ignition off with the throttle WOT. ? im boggled
i always had that code though, I just went to gas station for a fill up(sputtered my way there) and i filled car up with supreme and used some seafoam and the second i left the gas station there was a difference, the car was working almost perfectly and was working good like it for about 30 minutes but now its starting to get bad again, like if i ease the pedal to the floor its pretty good but as soon as i put go WOT it sputters and slows down pretty much, its almost as if i turn the ignition off. New plugs and wires and still nothing.
And i never took the 2 egr valves apart but i put a hose on the vacuum line ports and sucked and blowed and it seems to be moving inside and not sticking or anything
1999 mustang sputtery at high rpm 
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