My 98 blazer tps is only working with the key in the run position. While looking at it with my scan tool it works perfectly with out the engine running. When I start the engine it fluctuates around 3% and WOT only brings it up to around 9%. I have watched the scanner and wiggled all the wires and connections from the ECM to the TPS and didn't see any drops like I would for a shorted wire.

Any suggestions what would cause that, I'm leaning towards ecm failure.