Hi. I recently had oil pump failure at 247,000 miles. car was shut down immediately. replaced the oil pump, water pump and timing belt along with new crank bearings. replaced new full synthetic oil. when the car started it had tapping on top end. inspected rockers and found them to be collapsed. I replaced both sides with new oem rocker assemblies. started engine now the engine is exremely loud on top end. I checked for good oil flow all seams to be ok. I checked engine codes and it read intermittant loss of crank or camshaft signal. I replaced both and code is still present. engine seems to load up quickly gets warm and then is hard to start. there seems to be excessive oil in plenum and at one point had blown a section of the plenum out. could anyone tell me if a bad head gasket would cause this?