S52 track car random misfire

[pshooter]

I’m posting this here because the conditions that make this misfire occur would more than likely
Only occur on track.

After a handful of laps at LRP Check engine light comes on car drops cylinders. Pit and shut it off then restart runs fine. Go back out same thing.
When I got home P0300, P0305,4,6.
Pulled the M50 manifold and made sure all the Turner conversion bits were sealed tight and no leaks.
Cleared codes and off to the Glen.
Same issue However after multiple sessions the cyls detected were not always the same 1,3,5 , 2,4,6
Cyl 3 etc.

I can run 10 + laps at ¾ throttle shifting at 6500 and no issue. As soon as I go full throttle for any length it shuts off cyls.

S52 schrick 264 cams, M50 manifold, 24lb injectors,11-1 pistons, Porsche MAF, 180 deg thermostat, raceland supersprint replicas, 3” exhaust, Fuel starvation pumps.

Next step is high tension leads make sure no oil / water in plug wells. I’ll peek at the plugs while in there, but plugs are new, coil packs are recent. Probably a leakdown just because I’m right there.

In all the previous threads I’ve looked at there’s no smoking gun.
Any pearls of wisdom / experience appreciated.

[olemiss540]

Multiple misfires could be intake leak, MAF, O2 sensor, fuel pump.

[niemanj]

This is exactly my problem. What was the solution in the end? Pls reply as I’m getting desperate.

[pshooter]

Ended up being a head gasket.

[olemiss540]

Ended up being a head gasket.

How did you end up diagnosing? Compression test? Coolant system become pressurized?

[pshooter]

leak down test.
Was pressurizing the cooling system.
Also had signs of leakage between cylinders.