So this morning I was driving noth on I15 from my house to a school about 30 miles away. Everything was going great truck was running great, motor was about 192deg and the oil pressure was just over 40psi voltage at 14volts. I have about 5 miles to go I am just getting of the interchange and all of a suden my truck feels like I am towing some big ass heavy trailer and I start to slow down, I hit the gas to try and regain speed but my attempt failed and I continued to loose speed and then the motor started to back fire through the carb. I was able to make it to my exit and rolled to a stop at the red light. I put the truck in neutral and reved the motor, nothing sounds out of place, the light turned green and I put her in second gear and started to go. I was doing ok nothing seemed to be wrong I was able to shift thru 3rd and 4th with no problem no drag feeling anymore. I was able to make it to my destination. Once I was finnished I decided to head home via a state road that had a lower speed limit so if I was going to have any more trouble I would be able to get off safely. Once I got to about 5 miles from home I stared to feel the same thing as before drag and popping from the carb and a slowing truck with a double trailer deisel behind me comming up quick. I was able to get off the freeway and down the ramp to the red light. Once at the light I put the truck into neutral and gave her a rev, nothing seemed wrong. The light turned green and I was able to make it home with no other issues. So what the hell happened????? I have no idea of even where to start. Please HELP!