Hi, Anyone got any ideas to this one , Bus has been running really rough lately, Okay in first and second but into third and fourth and he's not happy kinda feels like there is something holding him back, so I bring it back down to second to get some more speed up, and shift into third and then fourth and he's okay, he backfired a couple of times last week has'nt done it since but he's not his normal self, I wondered if one of the jets could be blocked or if the petrol was getting through properly???. any ideas
