set the carb back to the factory settings and try from there. the trx2.5 can be a very picky engien to tune. if that doesnt work then you might have an air leak, you can find an airleak by letting the engine idle and spraying some soapy water around the engine and look for bubbles. another way is to spay wd40 on parts of the engine and if if it cuts out or stalls then you found the leak.