yeah I was going to say that if its really super cold where you are, nitro engines will naturally run leaner than normal. This is because the cold is more dense than warm air. So there's a chance that further leaning is just making it far too lean. But get the tuning right and nitro engines should run sweet in the cold.

Also another suggestion & I can't stress this enough. Always make small adjustments on the needles and ony adust one needle at a time. First set the HSN, then the LSN, then idle speed if necessary. Also its very important to allow the engine to operate for a few minutes after EVERY needle adjustment. If you adjust the needle and then after 30 secs think its not doing anything, you'll get it way out tune if you adjust it further or worse if you go back the other way. You have to let the engine settle in to the new setting. Yes it can be a lengthy process and if it takes a tank to tune, then so be it. Patience is the key.