Pilot of 182RG complained that he couldn't get the required RPM in flight.
It appeared that the engine cowling was fouling the prop control. Adjusted ground run satis.
Pilot came back with same problem once airborne.
While discussing it he mentioned that he had been getting bits in his water drain from the right tank, but not the left for some time.
Investigation lead to a roll of masking tape swimming in the right tank minus all of its adhesive!!!!!!!!!!!
The adhesive was all through the fuel system and was partially blocking the fuel filter leading to the RPM loss.
Lucky man as he regularly flew it over the Alps.