Check engine light

3 weeks go the "check engine light" on my Jeep went on. The retrieved code was P0303 - cylinder 3 misfire detected. The spark plugs and ignition coil assembly were replaced. Yesterday after I came out of the grocery store I started the car and stepped on the gas, when I put the car in drive, the car started forward then I felt a slow down in power and had to apply more pressure to the gas pedal. The "check engine light" immediately went on. When my mechanic checked the code he said it did not make any sense as the system read that the problem occurred while the car was turned off? Because the code made no sense, he said it would be difficult if not expensive to try to detect the problem. He said he would reset/turn off the light and that I should bring it in the next time this happens. Obviously something is wrong because I felt it and I am now concerned about driving the car. I asked him to recheck the work they did 3 weeks ago. Any other suggestions.

I have a 2001 Jeep Cherokee sport. The battery gauge swings from low to mid and my 'check gauge' light periodically comes on, then goes off. I don't know if it's related but my autostart won't keep the engine running: once it successfully starts, it shuts off, then starts again. Can't be awesome for the starter.

I have a 2001 Jeep Grand Cherokee. 137,000 miles 4.0 liter enging.

The check engine came on and the engine started to idle rough (as if there was a constant miss fire). As I accelerated it was jumpy and rough and the check enging light started to flash. As I got to speed and stayed at a constant speed it smoothed out but when I accelerated it started again.

Could this be a wiring harness problem since it has never been replaced or could it be something else.

After Thanksgiving dinner, started driving home. Halfway home, car sarted to shake terribly. Since I was only a mile from home, I slowed down and drove home. There was smoke coming from the rear center of the car, probably from the rear axle. What's up?

Hi -

Yesterday on my way home from work, my "check gague" ligth came on & then my temperature gague suddenly went all the way to hot. I drove it home 25 miles. As I was almost home, the light went off and the temperature went to normal. This morning, on my way into work it suddenly went to hot again. Half-way to work, the gague went back to normal reading.

I checked the coolant & the reservoir was completely empty. The mechanic checked for leaks & could not find one. He is giving the car a flush and new cooant put in. The check engine light did come on after I got to my office and recranked it to take it around the corner to the mechanic.

My question for now is: What kind of damage, if any would the engine have endured from me driving it that way for 50 or so miles? I have put close to $4,000 into repairs in the past year. I need to decide whether or not I need to start looking for a new vehicle.

Thanks!