I got a pro .15 nitro engine that powers my nitro sport. I was having some problems with is cutting out bogging ect. I took the engine into my local hobbie shop and they tuned it. the guy told me that the problem of it cutting out and boging was still there, just not as bad. to get the engine to run WOT i have to steadly press the throtle until i have it it WOT. i checked the motor for air leaks and there are none. There are new fuel lines and a new plug installed in the motor. The problem is not as bad is it was, but it is still there. Any ideas as to what it could be? this is really really starting to get on my nerves. is it a leak in the gas tank maybe? This engine only has 1 gallon run thru it, so i really don't want to buy a new engine. thanks for your help.