okay so i got this 92 C1500 V6 that idles really low it drives okay till at about 60-65mph and 2.5rpm if you shift to 5th it starts to lag really bad and really cant keep up rpms stay low even with the peddle to the floor board and clutch is not slipping kind feel like i am losing power in all the gear but 5th just will not do much i was missing really bad but i have changed the plugs an fuel filter and got rid of most of the missing any help please .