Intermittant Smoke

[Johnny Rotten]

Thanks for all the advice on boost, tranny temp and egt temp. Just got back from the weekend and the truck ran good although a little slow going up grades. But at least the hose didn't blow off. One thing did happen a couple of times, the boost gauge would fluctuate from 5 to 7 psi, the truck would act like it was miss firing and a puff of black smoke would come out the exhaust. Does anyone know what might cause this? Thanks again for the hepl!