Just did the valve cover gaskets and now have a rough idle and flashing check engine light..any advice appreciated!

 

Pull the codes.

 

Year and model would be helpful but I'd bet one or your plug wires or ignition coils or ignition coil connectors is not properly seated.

 

its a 2003 GS300
thats what i was thinking it was throwing codes for cylinder 1,3,5 so we replaced all spark plugs gapped to .44, the coil packs and wires.
after replacing those the check engine will flash for about 30 seconds the go off for a bit then back on and off and no codes come up but its still rough idling around 500 rpms

 

2003 gs300 replaced spark plugs coil packs and wires still rough idling
check engine flashes then will go off then start flashing again with no codes coming up