Thread: Help with SES codes, engine surging.

I have a 2005 Grand Prix w/ 130,000 miles. Sometimes under acceleration the car surges as if it's trying to find the proper timing. Usually I can turn the car off and crank it back up and it drives normally.

So, I replaced the plugs, wires, and O2 sensor (Bosch, which I read on here afterwards was probably not the best brand choice, but that's hindsight now). Surging seemed to go away, but is now back. In the past it never had an SES code, but last week it coded a P1134 and a P0133. Any help on what is most likely causing these issues and codes?

This is my first post on the forum, although I have visited here quite often to read up and kill a little time while at work.

I should add that when the engine is first started it seems to be under a load for a moment, then seems to clear out after a second or so and the RPMs come up to normal idle. Occasionally, when warm, the engine will shut off after starting and must be restarted and revved a little. After a little rev when started, it idles fine.

When the car surges upon acceleration, it is noticably harder to maintain speed and accelerate at highway speeds. This too goes away if the engine is shutoff and immediately restarted.

The engine consumes no oil or coolant to speak of and is regularly maintained. It does have a K&N air filter but does not seem to be over-oiled. I've owned the car since new and have had no other problems with the vehicle except for a coolant temperature code indicated a discrepancy between the incoming air temperature and the temperature measured at the throttle body, as explained by the local Advance Autoparts manager (a friend of mine).

Quick update - the SES light went off when I left the office yesterday and has not come back on. However, when I started the car this morning and drove down the road, same low power/surging without an SES. So, the surging happens both in open and closed loop operation. No SES light accompanying the problem this morning.

Please offer any suggestions. I've read MAF, catalytic converter, O2 (event though new, Bosch has problems) as possible causes here on the site. Which of these seems most likely given my symptoms?