5_labs, 1st, When the truck stumbles do you get black smoke from the exhaust? You might have your floats set a little high. 2nd, If your truck has an elec choke, you can ajust it back a little and that will fix the high idle problem. There should be 3 screws on the cover of the choke thermostat. If you look real close there should be index lines on the cover. Loosen the screws and turn the cover back untill the choke opens sooner. This should take care of the problem and let the high idle kick off.