hi we got a 2.0 4G63 mpi galant manual in. original problem was a blown head gasket (oil in coolant).
This was done and a new head fittied due to the head been to warped to skim, We also replaced the radiator, thermostat, top and bottom hoses and flushed the cooling system. on start up the car runs then begins to miss. The cooling system was still over pressurised, top hose solid. A block test revealed another pressure leak and we suspected a craked block and the heater matrix had also blown. we have replaced the short motor and heater matrix. This then appeared to have cured the fault but 2 weeks later the car came back in missing slightly when driving. we have tried the air flow meter, re-set the Tps and stepper motor, replaced the plugs and both coil packs and leads. There are no trouble codes in the ECU and the data list on the MUT is identical to the data list printed in the workshop manual. we have yet to try injectors and will carry out another cylinder compression check and coolant pressure check. Has anyone out there ever had a similar problem any help or ideas will be appreciated. thanx.