well, here are the symptoms -

> car starts and seems like it is running on only 7 cylinders - it
doesn't matter if the car is hot or cold when started. however,
there are times when it runs well, although more often than
not is runs poorly.
> rotors and caps replaced at mechanics suggestion - also
checked spark plug wires - could find no arcing
> if i put the car in drive and sit there with the brake on, the
problem is worse than just idling in park. in other words, its
worse when under load.
> just noticed this today - problem is aggravated by running
blower fan on high when ac is on. no problem when just using
the fan without the ac on - did not try heat to see if it does the
same.

can anyone shed some light on what the nature of this problem might be? would a bad alternator cause this to happen? could it be the wiring harness? thanks in advance for your help.