I hope you folks can help me.....I have a 2002 Malibu and it revs/surges/chuggles at
highway speeds by 200 to 500-rpm. It does it intermittently and enough to kick it out
of cruise-control, but not enough or long enough to "code". We have changed a whole
spectrum of things....four different shops....two were dealers. We changed out all of
the fuel-injectors, MAF sensor and a brake-switch. No go. Then, dealer flashed the
ECM/ECU. No go. Then, we changed out the torque-converter, torque-converter
clutch, pressure-control solenoid, hydraulic-valve, shaft and sleeve (per TSB). No
go. Next, we changed the throttle-position sensor and the ECM/ECU itself. No go.
I got opinions from two shops, one a dealer, one not. One sez to do more trannie
work like change-out the valve-body or replace the trannie in full. The other sez
it could be a glitch in the PROM for the ECM. It was NOT changed when the ECM
was. What does anyone think? Think it could be the PROM???????

 

sounds more like a tranny problem. change the oil and filter, check the pan for metal filings. if it still does it, it will need to be rebuilt or replaced, which ever is cheaper.

 

Trannie has been worked on...torque-converter replaced, torque-converter
clutch replaced, pressure-control solenoid replaced, hydraulic-valve replaced,
shaft and sleeve replaced. No go. It still did the rev/surge/chuggle. One tech
sez it could be the PROM and another sez it could be the trannie's valve-body.
How does one check that? Oh, it generally does NOT do it under 60-degrees
ambient temperature outside.

 

We also did a trek to Atlanta GA from MN and it only did the rev/surge/chuggle
for the first hour of the twenty-hours of driving time. Same on the return-trip,
only an hour of the problem the whole of the route home......