Truck has a mind of its own? help
So it started a couple of weeks ago. I was driving down the road and all of a sudden the truck decides to just give it self a little bit of throttle. This got my attention real quick. The truck belches black smoke every time it does this. The cel came on every once in a while but all this week it has been on, just haven't had time to fix it. The idle is also jacked up, its just fine at start up but after a minute it jumps up to 1200 rpms for a couple of seconds and settles down to the 800's which is higher than normal.
My truck had an edge box on it till today. I thought maybe it was the problem, but it wasn't. I took the box off and started my truck back up and it idled fine so i decided to take a test drive. This was a bad move. The truck ran fine for about a mile. As i was coming to a stop sign the truck just shut off. Started back up but as i gave it some throttle in neutral it was throwing a little bit off black smoke.
Problem number 2 is as i left the stop sign i went about 2 more miles and the truck started shifting funny. it didn't want to shift, hanging in between gears and the tow haul light started flashing. never had any problems with my truck ever till now. This kind of has me all bummed out need all the help i can get thanks.