Doesn't sound like too much of an issue. Some minor tuning and 10 minutes should have it running clean. Are the needles set as from the factory? Normally they send them running a touch rich for breakend purposes. Where are you? Until your comfortable doing it yourself. I would take it to a track or back to the shop and let someone help you the first time. It's a great motor and runs great went tuned right.
Thanks Bigmax, We set the top end richer and it solved the problem. I think it was related to a new can of fuel. It is a great motor - this our first nitro car and the power and performance are amazing. Thanks for the help