I have a 93 Escort LX, 1.9 liter, 4 speed, 90,000 miles. When I press in the clutch to shift gears the engine will rev up about 500 more rpm for 2 or 3 seconds then it will settle back down to idle. I have changed the EGR valve, Throttle position sensor, fuel presure sensor and idle air valve but the problem continues. Sometimes when I'm driving, the Check Engine light will come on but will turn off again. No luck in reading any codes. This is starting to drive me nuts!! Would appreciate any help or ideas.

 

Maybe the throttle cable is sticking a little? Disconnect and put WD 40 in it. Keep moving the cable in and out to lubricate it.

Thinking of it; I would clean the whole throttle body inside and out with CRC throttle body cleaner.

Next thought: vacuum leaks. Look for deteriorating hoses etc.