I have a 94 22Re 2.4 4 cyl. after market heads, stage one cam, downward headers k&n air filter the engine has 24k miles on it and I recently blew a head gasket on it. I had my head plained{ second time its been replained} and my valves reseated.since the head has been back on its been serging and overheating with thermostat in when i remove the thermostat it dose not overheat and only serges when engine is cold.Ive put alot of money into this truck ive replaced alot of parts{fan clutch,radiator,4 differnt thermostats,ect} one mechanic told me he thinks its my timing causing this{distribitor is turned all the way to the right its up against the bolt} and a adjustable cam sproket would fix my problem if any of you out there can give me any further advice before i purchase a part i might not need please let me know

 

Serging is often caused by a vacuum leak. I would gab some carb cleaner and spray a little long the head gasket, intake manifold and by vac-lines.

if the rpms of the motor change at all the carb spray found a leak. The temp being high also points to a leak in the head or head gasket.

Taking the stat out, would help, as there is no water restriction so it moves through the head faster. Well the whole system.

The dist being all the way advanced can also cause the rpm up/down thing to happen. But I would start with the carb spray to look for a leak, it don't take much, no need to soak things, just a little spray should work.

I guess a compression test would also tell you if you have a head gasket leak. I know they were just replaced, but some times that don't mean a lot. Mistakes happen putting things back together some times.