Small Aircraft
Flight Crew Commercial; Flight Crew Instrument; Flight Crew Multiengine
Flight Crew Last 90 Days 74; Flight Crew Total 2773; Flight Crew Type 2664
Troubleshooting; Confusion; Distraction; Situational Awareness
Aircraft Equipment Problem Critical
Flight Crew Overcame Equipment Problem; Flight Crew Landed in Emergency Condition
Aircraft
On go-around Aircraft X had a gradual loss of power which resulted in having to land in a nearby field. The airplane had been sitting (pickled) for three years a week before but had recently been flown from and to maintenance for the annual inspection (at ZZZ) and back to ZZZ1. The same day the off-field landing occurred; I had performed several landings and had no problems at all with the aircraft until this last takeoff/climbout.The RPM seemed to drop and the aircraft was not producing thrust. The engine has a massive carb heat system. Carb heat was used and possibly left on in the climbout however nobody thinks that carb heat would cause enough power loss to cause a catastrophic thrust - lift scenario in low density altitude flight conditions (sea level 65 degrees).Other issues might have been debris in the recently fueled tank; carburetor float issue and then possibly a prop governor issue. We could not reproduce the problem on the ground. So far; the issue is unknown as to the continual loss of power.In looking back at this event; I think that it would have been prudent to take a newly run aircraft that has been sitting for a while and just out of annual to a large airport where there is more room for errors. Only after several hours or days of 'testing' should you exercise an aircraft to other shorter riskier areas. You just never know what can go wrong. They say hindsight is 20/20 but I will need to take a better look at risk management when it comes to flying an aircraft that has an unfamiliar history or has just come out of hibernation and or annual inspection.
GA pilot reported engine failure while climbing out from a go-around.  Reporter successfully landed in a field near the airport.