Torque Conv Lock Up issue SOLVED!!! 96 Sport
 

Had the transmission rebuilt last year. Started having TC lockup issues shortly after.. Shop changed the solenoid etc. Seemed to help a bit. But last few months the TC would only lock up for the first 15 minutes or so of driving. Don't know if the problem was related to last year's problem or not. Checked OHMs on harness. OK. Changed TPS. No difference. Serviced all grounds. No improvement.

Figured it had to be the MAP sensor. Got a new one from Rock A. Installed today. Problem solved. TC locks better than it ever has.

Lesson: At 315,000 miles any sensor not yet replaced is suspect and should be replaced anyway just out of prudence and precaution. After all, how much can you expect out of these old parts?

Figured bad MAP was sending a high manifold pressure signal to the computer, which made it think there is a high load and should not lock the TC.

Easy enough to test, no need to guess:
https://troubleshootmyvehicle.com/je...e-map-sensor-1