well if u dont want to spend money on servos.....then i suggest making sure that u have NO cell phones within like 10 feet of ur rc car when ur using it becasue i did that once and someone called my cell phone when the car was right by me and then thing just took off from idle goin like 15!!!!!!!!!! also check for some metal on metal contact that u could prevent, and the antenna tubing that is still on the chasis put in fuel line to also prevent glitching! and about the engine, ull have to give us more info on that like ^^^^^^^said.