could be either, both or none.
none: the 5 volt reference wire, or any of the connections it makes, is getting flakey and will intermittently not be 5 volts, or another sensor which uses the same 5 volt line is drawing too much current and dropping it down.
both: well, it'* possible, and there could be many causes.
either: if the TPS is becoming inconsistent, then when the throttle is closed, it may not drop down to the normal voltage that the ECM expects at closed throttle. look at TPS voltage when it'* acting normal and odd as well, it may provide some clues. if the ECM can't keep a good regulated +5V line, then other sensors may start acting funny as well.
1995 Monte Carlo LS
3100, 4T60E, OBD1 Conversion...for now, future plans include a 3900, T04E-46 (Knock-Off) turbo, and a F40.