420A Repetitive Misfire codes P0300 to P0305

[ECLIPSEGS2]

I'm fairly new to DSM, just got a 99 gs 420a 5spd. However I noticed that the CEL/SES keeps coming on for multiple random misfires, and misfires on 1,2,3,and 4. I replaced plugs, wires, coil pack, and checked each cylinder for build up/ carbon. However whenever it pops these codes I dont feel any misfires but at low rpm below 3.5k rpm engine braking and light accel it pops alot. Im at my wits end for what could be wrong with it.
Codes P0300-P0305

 

[ECLIPSEGS2]

You need to determine how the oil is getting into the cylinders. How many miles are on the engine?

About 179500

 

[ECLIPSEGS2]

About 179500

I have very little maintenance info from PO but I believe HG is going

 

[ECLIPSEGS2]

You need to determine how the oil is getting into the cylinders. How many miles are on the engine?

I guess this thread can be closed however thats done, headgasket blown and carbon build up is causing bad combustion

 

[BLACK'98DSM]

I find it odd that your compression readings were 200+ on all 4 cylinders with a blown headgasket. Have you drained your oil and checked for coolant? And you didn't see any coolant in the cylinders?

 

[BLACK'98DSM]

The larger passages are the coolant passages and the smaller ones are the oil passages. It would be a unique headgasket issue to get oil in the cylinders but no coolant in the cylinders. And no coolant in the oil. It is definitely possible especially with the factory head bolt torque issues, but you see what I mean?

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[ECLIPSEGS2]

I find it odd that your compression readings were 200+ on all 4 cylinders with a blown headgasket. Have you drained your oil and checked for coolant? And you didn't see any coolant in the cylinders?

Oil pressure is forcing oil into cylinders

 

[ECLIPSEGS2]

Oil pressure is forcing oil into cylinders

Had it happen on my last car just worse

 

[ECLIPSEGS2]

Had it happen on my last car just worse

Last car burned 2 quarts of oil in 6 miles, also 4 cylinder, and the HG is oe at 179500ish PO told me he never had it done

 

[BLACK'98DSM]

Show me where the oil can enter the cylinder without also entering the coolant.

 

[ECLIPSEGS2]

Show me where the oil can enter the cylinder without also entering the coolant.

Checked the coolant it is clean, used a scope and poked around in there, saw no signs of leaking valve seals. However I noticed a major oil mess on back of the head near Head and block are separated by the gasket spanning across cylinder 2-4 when running it became a seepy and started leaking.