I am looking at a nice 99 F350 SRW 4x4 (189K) with a Bully Dog GT, straight pipe, K&N and wicked wheel in the turbo. He says that every now and again the TPS acts up and he says its like it doesn't respond to the gas pedal. He says its a cheap part and he just hasn't gone around to changing it. I like the truck but wanted to make sure he misdiagnosed it and its something else costlier. Also he has an Air Dog II separately that isn't installed and wondered if that was worth me offering more money on?