I bought a 2000 mojave 250 about 2 months ago. When i got it i found that i could start the quad and that it would idle but when i gave it throttle it wouldnt rev past 1/4 throttle and when i give it full throttle it will go back down to an idle. So i changed the oil "knowing that would help the issue but was needed". i also rebuilt the bottom end of the carb, replaced the diaphragm on the top of the carb, replaced the spark plug and cleaned and re oiled the air filter. the adjustment screw on the bottom of the carb is set to 2.5 turns out. After all of that it is still acting the exact same. What should i do?