When you put a new rod, sleeve, and piston it in did you also replace the wrist pin? What you problem sounds like is what the engines do when they are stillnew and tight. These engine take 1 sometimes 2 gallons to fully break in and when they are tight like that you have to run the idle a little high or it will get stuck at the top and die on ya. at 100 degrees outside 240 might be a little rich still but thats actually good if your still rich. These engine take so long to break in it really isn't a good idea to do a break in of 5-10 tanks then take to the track to race it. Most times I have seen people do this they run them too lean while they are too tight because they want max power now, this wears out the engine and you will loose compression FAST.Try getting out for a practice day and just run it and run it and run it and you will notice it will get faster and faster the more fuel you burn thru it.