C140 pilot reported loss of power on initial climb from a touch and go and a safe landing in a field adjacent to the airport.

Narrative

I was flying a left closed traffic pattern off of runway XX in my cessna 140. In the landing proceeding the loss of power I performed a slip to lose some altitude. Approach and landing went well; I performed a wheel landing and allowed the tail to come down before applying power for takeoff. Takeoff was normal until I was at about 100 ft AGL. At that time the engine RPM dropped to below 1;000 (basically idle power) I immediately applied carb heat as I have picked up carb ice many times in aircraft with the same engine Continental 0200. But I never have had RPMs drop this much due to that. Taking off of runway XX there are trees about 1 mile off the departure end and I was maybe 1/2 mile from them at this point. So; I [advised ATC] and decided to turn left about 40 degrees parallel of runway XY which was more into the wind as well (variable from 290-330 at 11 Knots); I considered landing on the last 1;000 ft of runway XY but did not have the altitude to do so. The engine surged several times which gave me a second to aim for a somewhat flat and mowed spot and ample altitude to clear a drainage ditch. I opted for a 3 point landing to limit the risk of a nose over and to allow me to land at slower speed; I can't remember if I used flaps. As landings go it was a good one under the circumstances; there were several bounces due to uneven ground but nothing of severity or to cause any damage to the aircraft. After coming to a stop; the engine sputtered several times before it began running as it normally does. I was able to taxi the airplane back onto runway XY and return it to my hanger. All system seems normal.After looking over the airplane and all seeming normal (Further checks will be done) I believe the cause of power loss to be a fuel flow issue; During the slip the left wing was down which was the side of the fuel tank I was feeding from (Cessna 140 can only feed one at a time) the tank was half full at the time of slip and I believe this may have allowed air to enter the fuel line. I think the lines had enough fuel in them to allow for landing and takeoff but eventually it made its way through to the engine after takeoff. This is just an educated guess on my part but unless anything abnormal is found I plan to only slip with the fuel selected on the high wing or only if the low wing tank is on full. Making a uneventful off runway landing was possible due to large areas of relatively flat treeless areas around all the runways.