TPS? I don't know. The best way to find that out is to do a quick voltage check. Mine was bad and it just idled poorly and had some hesitation off the line.
Not being able to peel out is either a power or driveline issue, and if the car has good pull on the road (Mr 5.0 has a good idea about the track), chances are its the driveline (much like chipdog said).
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1995 Mustang GT