99 Trooper p0121

TPS circuit out of range. The thing is, the TPS tests good with a high end graphing meter. No drops, upper and lower voltage within spec. I don't get it.

If the TPS is good, then you need to check the continuity of the circuit between the TPS and ECU. Check for resistance or fault to ground of each wire. You could also check the TPS voltage @ the ECU.
Danny