My 1994 Model Space Wagon, after having an engine overhauled , started to incur trouble particularly in idling. The idling or the RPM fluctuates (goes up and down). And during travel to hilly part, the engine loss its power and it doesn't accelerate thus make the engine automatically shut down. Is it possible that there is water that mix in the fuel going to carburetor and the engine hardly burn the fuel because of the presence of water.