Couple of weeks ago truck started to mis-fire, kicked out a lot of black smoke and then ran OK but engine lite was on. Pulled the codes and replaced the EGR - it was clogged with a big chunk of carbon. Then the truck blew the P0300 code so I changed the plugs and wires. No change. Couple of days later on the highway the RPMs dropped to zero and then back up and ran OK. Pulled codes and found P0335. Just finished replacing the crankshaft position sensor. Erased the codes. Took it for a drive and the P0335 code is gone but I still have the P0300. Also, for the past couple of weeks, occasionally the truck fails to downshift (A/T) properly when coasting and often when it runs rough my cruise control will not work after the roughness. I've got a boat that really wants to get wet doing some fishing but not too comfortable taking the chance on getting stuck somewhere with a boat attached. Any help would be much appreciated! Thanks

 

Welcome to the site.

Since you have already done the plugs and wires and still have the P0300 (random misfire), try swapping the coils from where they are at now to another cylinder but keeping track of where they were at and where you moved them to and see if it goes away