What can I do if the diagnostic scan doesn't reveal a misfiring problem?

Thanks for your help! I'll have someone look at it

In both cases, mechanics. Why, does it make a difference?

Yes. big difference in reading codes off a scanner and actually using the info to DIAGNOSE. OBD2 if your truly experiencing an ignition misfire , as opposed to an intermittent fault in another system that exhibits similar symptoms , then it should be seen on the live data under 'misfire counter' or something similar.

Thank's) As for your trouble with the engine, has a MECHANIC had a chance to look at your car when it was acting up? Better yet with a GOOD scanner hooked up at that time? There are a lot of code readers that aren't designed to troubleshoot! However, some intermittent problems are verry hard to find. Hang in there one of your guys will find it! Good luck.

And I don't think a compression problem , timing belt off a tooth , or sticking rings are problems that would fix themselves on and off for almost a year. DON'T forget the BASICS and forget the scan tool for a few minutes and use a vacuum guage. EYES are used on spark plugs (possibly with some magnification) to reveal other existing problems. Any history of body work would warrant an inspection of all grounds. ALL just random thoughts from an idiot. Hope they help.

To wetry: The mechanics have asked us to bring it to them when it acts up, course the problem is you can never tell. Once we were on the way to them and it cleared up just before getting there. But thanks again for your response, I'll go back to the dealers and ask them to tell me EXACTLY what comes up, or as ziptie suggests get back to the basics. To ziptie12: Hey, random thoughts from an "idiot" just may solve this thing, so here's a big thanks from this idiot :)

PLEASE let us know what the progress is , if any yet.

None yet, since I need to raise the dough to go to get it checked. Sigh. It's been a truckload of money problems recently :(

Been there , not fun. Hang in there.

UPDATE: Finally! It's been solved and you'll never believe what the problem was. There was a reason nothing showed up on the scan; it was just that a connection was loose. Literally. My boyfriend decided to take the bull by the horns and replace parts piece by piece until the car was fixed. Since we've been getting advice from just about every body under the sun, we started with the coil pack. But after changing it (he did it himself after being shown how easy it was) the engine was still misfiring. It was only on checking the cables (if that's what they're called) that are at the end of the coil pack and fit into the engine/near the spark plugs that he realized one of them was actually quite slack and sliding off slightly instead of fitting flush like the other. After experimenting, he saw the difference in engine idling with the cable loose and then with it fitted. So, a little tape later, voila, the problem is solved (albeit spending unnecessarily to buy a new coil pack since the old one was perfectly fine). But I'm just relieved it's finally over, and a little weirded out that one tiny thing could wreak so much havoc! Thanks anyhow guys. At least if anyone else has a similar problem, they can learn from my experience and always check the little things first before assuming it's a really big thing :) Seriously though, could you imagine spending a truckload of money and the only thing needed was a piece of tape? I'm still shaking my head