My '99 Camry V-6, automatic, intermittently loses some power as I drive (noticeable at speeds 50 or more). It feels about like an AC compressor turning on in a 60's era Chevy, but it is not the AC. The power returns but does so virtually imperceptibly. This has been going on for more than a year and I've taken it to several garages with no success (just lost money trying!). One place claims to have checked everything with a sophisticated diagnostic computer and found a "flat spot" on the Throttle Position Sensor. Replacing that, however, has not solved the problem. By the way, no codes are being set. Once in a while I can feel it (whatever it is) cycling in and out or on and off. I am at a total loss as to what could cause such a problem and apparently so are the places I've taken it to and have thrown too much money at it with no success.

Has anyone else had experience with such symptoms and know what to suspect? Any help would be appreciated.

 

Have no idea.

The TPS was a good guess.

A sharp drop on power? Might check the power steering pump and anything else driving by a belt.

The EGR might be opening too much. Fuel pressure variations, fuel pump, fuel pressure requlator issues can cause this.

The issue with trouble codes is not all the equipment is monitored by the computer. And the computer needs to have the problem occur under certain conditions most times at least twice before a code is set.

You might get a real time ODBII readout that will monitor the various system. You could then watch the output of certain systems for changes when the engine power drops. Might also monitor the fuel pressure by installing a gage.