So, here is my problem...A few day's ago I started the car up in the morning and it acted up. Idle was erratic with the engine seeming to surge, and the lights on dash and head lights would dim when the rpms dropped but brighten when the engine surged and rpms raised. This only lasted a minute and car ran normally after I put it in drive and drove away. Side note: I don't know if this makes a difference but the day before this happened I had a new starter installed. Moving on...A couple days after the morning incident my husband took the car somewhere, he returned 15 min later saying there was something wrong with the car. It was bucking and fighting him on the highway. He said it was bucking and whinding and having great difficulty getting up to highway speeds. The funny part is no CEL ever came on...I scanned it anyway and it gave codes for miss fire on all 6 cylinders. I drove the car 20 min later after hubby came back and got codes and the car ran fine, around town and highway. And I drove it for a good hour. The problem seems intermittent...And the no CEL coming on is cause for concern. I'm stumped. Only thing wrong with car is a coolant leak coming from upper intake, and mysterious ABS issues that seem to be pointing to a connector around control arm. Only recent work done has been new battery, re-built tranny, egr valve, new starter, new belt and the car had computer re-flashed before tranny work was done. So, all cylinders miss fire with no CEL coming on. Any clues?