draccent,
Which of the maintenance procedures specified by Lycoming would you feel constitutes a "full once over"? Would it be prudent to also examine the aircraft fuel system?
How much money would you propose that the aircraft operator spend to assess this momentary loss of power?
Would it perhaps be more effective to just replace the engine with a new one to be sure?
So as to offer a little assurance, I can tell you that the 152 can be safely flown and landed under power with any one of it's 8 spark plugs not operating, either of it's two magnetos not operating, any one of it's four exhaust valves stuck slightly open, or a 25% blockage in the fuel system.
My money's on the exhaust valve on this one.....
Pilot DAR