Engine problem when hot

I have a strange problem with my car, this has been going on for about 6 months, but only happens after driving the car for long distance (over 250 miles). Basicly after driving a long distance on a highway trip everything will seem fine at cruising speed, but the car has no power to pass, if I try to take off hard from a dead stop the car lurches and surges HARD. In extreme cases I can drop it into neutral stand on the gas and the rpms will not go over 3200, they will climb ok up to about 3200 then hang, if I keep my foot on the floor a couple of seconds later the car will start making an odd sound (running rich/lean? no pinging sort of sputering though) the rpms will slowly fall to about 3000 then climb back towards 3200. If I stop for gas or otherwise let the car cool down when on a long trip the problem goes away for a bit, but relativley quickly returns once I have driven a while. No codes are being tripped even when I stand on the gas in neutral (I have not dared do that for more than a few seconds though for fear of doing real damage) This happens at both partial and WOT, in case that helps I know the computer acts different and uses diffent inputs for each. Could this be a fuel pump issue? I know in the cooler months simply stopping 5 minutes to fill up the gas tank would make it go away for a good bit(the gas was much colder then too).

thanks for any help you can give my mods are in my sig.
Ike

I have not checked the TPS when this is actively happening, I do have a code scanner that will check it "next time", however I have only checked it after getting back from a trip after the car had cooled for 5 - 10 minutes (I had to go into the house to find it) at that time it seemed to be fine. It also seems that if it is heat related that something sitting on top of the intake like the TPS could not cool down in the time it takes to pump a tank of gas. Internaly its not that fancy either, no heating element like the MAF has, etc just a simple low voltage position sensor. I may just change it out rather than trying to test it, it is cheap and easy to change (2 screws).

Ike

I will try cleaning the MAF, it can't hurt to try, but why would it take several hours of driving before it started going crazy? Also I may be wrong, but I thought the MAF was not used for input by the computer at WOT? Anyone else have a thought, this has been going on for 6 months and I really need to make it stop.

Ike