fuel not reaching the engine due to rear shift of fuel in the tanks during a touch & go with high nose attitude / acceleration?
Nah. Unless you were just about out of fuel, this was not the cause in a serviceable system. I have many hours in my 150 doing horrible nose up attitudes (it has a STOL cuff on the wing). I have never had a burp form doing that.
A fouled plug will cause roughness, but not a noticeable power loss at a higher power setting, unless both in that cylinder are fouled.
Depending upon the symptoms, and time in service for the cylinders, you might have had a sticky exhaust valve, I've had a few of those, and the engine seems terrible at about 2000 RPM, but it will keep running, unless you stick two, then you are going down (or are very glad you are down!).
Ask the maintainer for a good discussion about sticking valves, this is what to watch for (presuming you're carrying enough fuel).