Serious engine trouble to come?

[Sledgehammer]

A friend of mine has had recent issues with his engine upon startup. It would hickup, and sometimes stall out until the engine warmed up a little. He continued driving for like 3 weeks after the first issue. I went over to help and try and trouble shoot. He has a corksport intake and cold air box. We took off the cover and saw that his air filter had come off and was just bouncing around inside the box. Im guessing that he has been running without an air filter for 4 to 5 weeks straight, and the stuttering was either from the dirty mass airflow sensor. That was cleaned properly, the issue is, what can we expect problem wise for the future, what could be done to clean the engine out asides from pulling off the heads and manually cleaning every part? Advise would be welcome and obviously necessary. He has a mazdaspeed 6.

 

[bova80]

i think you'd have bigger problems with the turbo before anything happened to the engine. i'd clean the maf, put the filter back on and see how it runs. maybe run some seafoam through, but if large pieces of dirt got in i'd think you'd have damage to the turbo.