Just bought this 2006 4.2 Envoy,runs good and sounds good for the most part,at idle it throws a p0300 and after a bit p0301
Compression good,did tighten intake bolts.swapped coils and new plug.Here is a log at idle ,below 750 rpm it has low timing,with idle up timing is up.Long terms go lean near the end.Please help see what I am not seeing Thanks.