My car started where it would lag when at full throttle, but now it no longer lags when i give the car acceleration. The car however, runs smooth but then i will feel the car engine shake for a second or two and then run smooth again. I think this is a misfire but i do not have any OBD2 codes. Does this mean it needs new spark plugs, or is there something else wrong?

 

Wayne,
You could take it in and get it scanned at an auto parts store in your area. Many of them offer that as a free service. Even if there is no check engine light, there may be a pending code or the misfire test may show as failed. If that is the case, you would probably get a check engine light and misfire code pretty soon. It sounds like a misfire in your description, but it should throw a code if it persists. It must be quite intermittent for it not to.

A can of injector cleaner could also be an inexpensive first step. I am told the GM injector cleaner is very good. You could check the plugs too, especially if they are overdue. I have been told they tend to create problems at higher engine speeds or during acceleration. Sorry, I have never really had a bad plug, having replaced them before failure. (still overdue though). I am not an expert at bad plug symptoms. I had an occasional misfire that ended up being a coil. It would run fine for weeks and then start missing, then run fine for a few weeks. It did throw misfire codes when it did that. I eventually determined it was a coil. Of course I replaced plugs first as it was a less costly first step, but did not turn out to be my problem.

Again, if it is misfiring, I would expect a code to appear fairly soon. The computer only tolerates so many before coding. There are many possible causes for rough engine. It would probably be a bit easier if you did get a code.

Good luck