I have a 2000 monte carlo and have a code of p0301. on 2000 Chevrolet Monte Carlo

code p0301 and overheating. replaced thermastat,water pump, and radiator plus it does not put heat out with the heater on

P0301 is a missfie fault detected at #1 cylinder. Better pull that spark plug and check for coolant getting in that cylinder. Could be a bad intake or worse a blown head gasket.
that plug does have more moisture than the rest. how can i tell if its the head gasket or intake
Give me more info about what size engine and I will get back to you Monday, At work I have access to more info. Have you had this engine overheat very bad and how long ago?
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The code is the egr valve, its easy to replace.