Van starts, but idles real rough for about 10 mins, backfires and jerks.

Have you still got the problem if so try fitting a new throttle idle motor ,it is fitted to the left hand side of the carb as you look towards the front this little motor controls your idle speed and keeps track of what you throttle opening is doing ,you may find that this motor is worn out,only a 15 minute jobby and really makes a big difference to your fuel consumption too.start your engine and watch for this motor to operate it can also stick causing your throttle to stay open even when your foot is off the gas ,can get a bit hairy ,worth a check..regards.Ps rockautos or auto parts warehouse.