kyosho .21 RTR issues

[Whitey04]

I've been having problems with the engine that came with the inferno 7.5 RTR buggy. Well not like new issues, more like ever since I purchased the car. The engine would never tune right, and before you ask yes it was broke in...right. I recently found that the carb was suction air though the slide throttle. I seemed to have fixed it, and I can kind of tune it, but once the engine gets hot it wont run or start, It has to cool off before I can getting it running again. I'd also like to add that I had taken it to leisure hours and while running it around, the air filter fell off! I don't think it sucked anything in, but I did take the carb off and the heat sink and I didn't see anything out of the ordinary. Now I was told by another guy that He's heard that the kyosho RTR engine had issue to begin with, and he's the one to point out the leaky carb. I'm new so I thought what it was doing was normal. He's also mentioned that he had an engine once that did the same thing and the engine turned out to be junk, it would get hot and lose compression. I'd just like a second opinion. I'm probably just going to buy another engine. But I'll like to work all the options out of this one.