3.3l motor. RPMs go up and down with no consistency above about 35 at part throttle. Does not do it coasting or passing, still does it if you put it 3rd. Starts happening after the motor warms up. Gas millage is bad ( 17 hwy ). Replaced plugs, wires, and coil pack ( brought mileage up from 14). No code, hesitation, smoke, soot, etc, runs fine other wise. Only odd thing is it started not long after oil change.
Have the cat converter checked for operation. It may be clogged. A shop can do simple testing to verify.
February, 17, 2012 AT 2:08 PM
No one here would do it without a lot of cost so for the price of a gasket I pulled the catalytic out and checked it. No melting or clogs, in fact it is fairly clean. While there I put in a new fuel filter. I also replaced the entire ground cable from the battery. Now the RPMs on go up when you use the cruise control. Could it be the 2 speed sensors?