CEL p0306 came on the other day. replaced #6 coil and #8 (cracked boot) and plugs. CEL p0306 again. Took to dealer and was told low compression on #6 and #8. Was advised to replace with updated cylinder head. Also the idle is low and funky. No ticking. Any Thoughts? Im in NY. Anyone interested or recommend somewhere for a head install? please help?