compression would check out OK because the motor would have been warm already, thus sealing leak.
you want to get the cooling system pressure tested. Or alternatively, the place I went to had a chemical test where they took some coolant and added a chemical to it to test for the presence of exhaust molecules in it.
But generally: misfire when engine is cold, to go away when warmed up = leaky headgasket
2002 Nissan Sentra SE-R Spec V Blackout
The Sig monster ate my sig