Thermostat ??

Well my car (91 accord) would shift through all gears fine in warm weather. When cold weather would hit, the TCC wouldn't lock up and gas milage would go down. :screwy: Also the temp gauge would run totally cold when crusin' down the highway and start to warm up when stopped at a light. I replace the thermostat and it actually fixed the problem. Does the temperature of the engine directly decide if the TCC locks up or is this just a coincident?

Yes, the TCC lockup, EGR operation, and a few other things are disabled until full operating temp is reached...