Just finished taking it for a run after changing the fuel filter, I revved it up and clouds and clouds of black smoke came pouring out for about a minute or 2, then it cleared and it started running better, took it for a run around and it seemed to be performing better, was no longer chugging when in a low gear and when idle it maintained revs. So I just wanna thank you for your help, and ask is it worth changing the air filter even though the problems seem to have cleared? Thanks