Without a code the best educated guess for me would be the TPS. Get your multimeter out and check the voltage. If it is the TPS then buy a good one, not a 10.00 POS from Autozone! I believe those have to be set up by running it through the range before driving. Or, it could be 1 of 50 different things... Pulling the error codes from the ecm is your best diagnostic tool.
1990 F150 Lariat 300 5 speed 3.55 ls C824's upgrade F250 3 inch leaf upgrade Centerforce II 11in clutch
silence is golden...duct tape is silver!