1st post, 2013 misfiring, engine light on, rough start, dealership

Hello,

I've been lurking (reading) on this forum for a few years. All of you have saved me a few thousand dollars and plenty of frustration. Thank you.

I currently don't have access to my usual mechanic, and had to take the car to the dealership with some engine knock, misfiring, and a check engine light on. The car has just under 230K on it. The dealership diagnosed as a likely head gasket leak, and quoted $5200 for replacement of the head gasket.

Foolishly, and unlike my usual self, I didn't look under the hood before dropping the car off due to being extremely busy at work in that day.

After returning from the dealership, there was some more engine knock, and I opened the hood. The first two ignition coils were not even bolted down, so they could be lifted right out. The phase sensor was loose.

I don't have a code reader (need one) or a multimeter, otherwise I would have checked the coils.

The car hasn't overheated, the oil didn't appear to have coolant in it when drained, and the coolant didn't have any sign of oil in it. There had been a few instances of oil odor in the cabin when driving. A hand sized area was stained just under the valve cover. I don't have a code reader (need one) or a multimeter, otherwise I would check the coils.

This morning I removed the air intake manifold (filthy, largely carbon, a bit oily) and the EGR pipe (basically plugged).

As I have very limited diagnostic skills, here is the empirical plan:

Clean the air intake

Clean the EGR pipe

Replace valve cover gasket

Replace plugs and coils

Replace o ring on phase sensor.

Refill with oil and coolant.

I've had the car for 12 years, bought used, yet I still want to keep it running if practical. Replacement of a head gasket may be a stretch for my skills and tools.

Any suggestions?

MD.