1)get an obdII reader and check for pending codes, specifically P0300 and P030x. If so the PO30x code tells which cylinder is misfiring, sooner or later a code will be thrown to trigger the light if this is the case. There are other pending codes that could indicate mixture adjustment out of range lean, usually means vacuum leak.
2) checking coil packs as you did won't IMHO really tell you anything.
3) any chance it recently had the engine bay get wet??
4) the tick could be the purge valve
5) unless ALL the other vacuum hoses have been replaced in the last 8years or so, I suspect you also have other vacuum leaks, giving you fits. since replacing the breather means removing some covers etc. highly likely some of these other hoses turning mush also ended up with cracks/leaks/or loose joints.
2) checking coil packs as you did won't IMHO really tell you anything.
3) any chance it recently had the engine bay get wet??
4) the tick could be the purge valve
5) unless ALL the other vacuum hoses have been replaced in the last 8years or so, I suspect you also have other vacuum leaks, giving you fits. since replacing the breather means removing some covers etc. highly likely some of these other hoses turning mush also ended up with cracks/leaks/or loose joints.
