Volvo Repair: car problem, cold engine, spark plugs

Question
It's part throttle and it mostly does it when the engine is hot. Sometimes when it's cold also. It does it while it's idling like when I'm at a stop light or something like that.
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Followup To

Question -
I have a 2000 S40 and it seems to have a problem accelerating at times. It doesn't do it as much without the air conditioner on but, with it on it seems to hesitate. I don't know if i should say hesitate but feels like it's a jerk.

Answer -
Well that particular model is sensative to misfires.  Does it do it full throttle or part throttle? Just starting off or anytime you press the gas?  Hot or cold engine?  You said more with the a/c on, which helps point me in the right direction but I just need more information.  Supply me with more details and I'll see what I can find out for you.

James

Answer
Well it sounds like an ignition issue.  It is most likely not your spark plugs but if you haven't changed them in 60k miles then you should go ahead and do that.  Check to make sure the ignition coils aren't coming apart. Alot of times they dry-rot and crack.  If you can't seem to find anything there you're probably going to have to take it somewhere to get a readout from the computer.  At that point there would be no more guessing and they would be able to figure out whats going on.  

James