where is your MSN? the only time i've ever had problems with tunning this engine is when the msn was wrong. A part from that it runs fine and never stops no matter if its a bit rich or a bit lean it'll will just keep going. 270 degree F seems quite hot to me. I'm flat out getting mine above 100 degree C (i'll let you convert that as i don't have the time to look for the exact conversion)