It's probably the tps then...make sure it's the tps, you don't want to replace a part thats good.

How does the engine feel under load?

What you can do is a tps sweep test with a multimeter. Get a thin wire and remove the connector to the tps, find the reference wire and put the wire in between connector and tps. Turn your key onto the on position but don't start the car. Put the positive lead on the wire and ground the other at the enginem move the throttle plate from idle to WOT and look at your voltage readings. It should go from like 1 to 5 volts. Actually check your voltage at idle and find out the spec.