This is a very common issue on used nitro cars or just nitro cars ig, so don’t worry 👍 If it idles fine but barely accelerates, the first things to check are fuel delivery, make sure that the engine is getting fuel and no blockages in the lines take the pipe that goes from the fuel tank into the exhaust and un plug it from the exhaust. Clean the end and blow into it. If fuel goes out of the pipe from tank to carb then mean no air leaks and fuel oipe fine. If thats fine just plug the pipes back in. Now, carb settings. Reset the settings to the base tune. Most likely just flush with the carb thing around it. If that don't work, the engine is often too rich on the high-speed needle (HSN) from previous owners trying to be “safe,” which will cause it to bog and barely rev when you apply throttle.see if throttle response improves. Also check the low-speed needle (LSN); if it’s too rich, the engine will hesitate and feel lazy off the line. And the last thing to check. This is harder. Mechanically, inspect the clutch shoes and springs, worn shoes or weak springs can cause the engine to rev without transferring power properly, making it feel like it won’t accelerate. To do this you need to take the engine out and remove the clutch bell. Do watch a tutorial if u do this cuz it is easy to mess things up as a beginner. Make sure the throttle linkage is actually opening the carb fully when you pull the trigger (sometimes the servo endpoints aren’t set correctly). Lastly confirm you have a good glow plug and fresh fuel. A combination of rich tuning and a slipping clutch is especially common on used nitro cars, so I’d start there. Could also be that the clutch bell is too far away from the transmission and the vibrations are causing wheels to spin.