I drive a 2002 Malibu that revs/surges/chuggles 200-500 rpm at highway
speeds. It does so intermittently. Yet, it does it enough to kick the
car
out of cruise-control. We have changed out the fuel-injectors, replaced
the MAF sensor and a brake-switch. No go. Then, re-flashed the ECM.
No go. We replaced the torque-converter, torque-converter clutch, the
pressure-control solenoid, hydraulic-valve, shaft and sleeve. No go. We
next changed out the throttle-position sensor and the ECM unit. No go.
One tech now sez it could be more internals of the trannie (i.e. valve-
body) and another sez it could be the PROM for the ECM. Does any-
one have any suggestions, other than trading off the vehicle?