Hey guys really stuck on this been trying to diagnose this problem for a while about 5-6 months wasting big money , the car is fine at first for about 5 minutes first starting runs perfect but then after a while it starts sputtering bogging out surging and when I'm on the highway driving for example I'm in 3 third gear and go to pass someone and open the throttle if I keep my foot down the car completely loses power as if it sloped in to neutral and with out Reving but I'm actually pushing the gas down , but when I pull over to the side and shut the car off it starts up fine and then runs perfect through the gears but then after another few minutes it comes right back check engine light is not on ! I've only seen a couple others with the similar problem it's my first car 2000 mustang v6 and would really like some help I've replaced fuel filter and in the process of cleaning the MAF and the other sensor that goes in to the intake tube , and new spark plugs and a cat back exhaust Because I thought the exhaust might of been bad although after the new exhaust the car ran good for a few hours which I've never experienced with this car , but then I did a " drift " poped up the hand brake stalled out and then this problem started happening it also happened shortly after I put some gass in the tank any help guys really stuck thanks and sorry for long description

 

Make sure you clean the throttle body, as you may have some build-up in there, keeping it from opening/closing properly.

Maybe a small leak in the EGR??? Hopefully you gapped the spark plugs correctly?
From your description, this is a 5-speed, correct?

Having owned a 2000 V6, the only other issue that i am aware of was a recall on the emergency brake system...not that that would lend to your problem, just an FYI

 

Well first drifting does not happen with an open diff on a v6. Also still could be exhaust, the catback isn't gonna make a difference on this problem as the problem is liable to be the cats themselves being clogged. Other possibilities could be the coil back going out. This seems like the most likely culprit from your description of it being fine on startup but acting up once it warms up.

 

Sounds like it starts acting up when the computer goes into closed loop mode.

 

Hello yes my mechanic has checked the cats so he says , and I'm aware that the egr valve was clogged or stuck but now it's freed up I've just recently cleaned out throttle body and my MAF i had a big slit in my intake tube have a k&n being put on soon the Hand brake wasn't with the car when I bought it , it was broken so another one was welded to the frame and installed as long as it isn't the engine it self or the tranny I won't give up on this car

 

What's this loop mode

 

There was snow lol ! And my mechanic said the cars were good he says he checked them as he was putting in the new exhaust I'm now going to make sure the coil pack is good