1st day out w/truck..end up on wrecker

[truck69]

You look to the 1st day of the summer out with your truck but it sometimes doesnt end good.My brother & his friend had my C20 for 3 mths. Redoing the engine(Put new cams..gaskets..carb) & brakes & Dual Exhust. Note: Even after this we still do have a bad Cyl. which we knew might still be a problem. I started the truck up..(sounded good). But after 1/2 driving to my home I could not get the truck to go above 50 mph and the engine was missing and the truck was slowing down. At this point I am going down a big hill. Not up it. I pulled into a drive way and when I came to a stop I noticed smoke coming from the right side fender. The truck would move back and forth but it felt like the brakes were holding. After calling a wrecker and a $120 tow bill I took it back to my brothers and he said it could not of been the ER brake because they disconnected it. He jumps in it and flies off and comes back after 10 mins. and says he finds nothing wrong. Does anybody have ideas of what the problem could be? Note: The person who did the brakes was just one of his buddies. Not a licensed mech.
Thanks Truck69