i need help

hi peeps i have a problem
does anyone have any ideas?
my car runs for awhile well, i have 2 stay at about 2 and a half thousand revs,,
after about 20 mins all power seems lost,, my accelorator does seem 2 work and i cant get power, i pull over for awhile n it works again,, im wel confused!!
any ideas??

diesel carb or gti?

or maybe is it a vr6 conversion!!

which engine lol

if its a gti i suggest looking in the fuel tank for rust or it could be the accumilator

Coil?

We're going to need to know if its carb or injection. Also, when you say you have to keep it at 2500rpm, why? Does it stall if you don't hold your foot on the throttle? Can you drive the car? Are you driving it at a constant 2500rpm everywhere (that must be hard)? etc More info please….