Tony, My Losi's have done the exact same thing in the past. Check the Tank exhaust pressure line. As well check the seal on the tank lid. Both of these have caused idle jumps in my rigs.My losi's running the stock losi line it seems to cause the idle to bobble before returning to normal. I swapped mine out to a 3/32 line and it cleaned the idle up. Monty will have some more suggestions but thought you might try that and see if it helps.