sounds like the pump relay is stuck ! as for the black smoke check the regulator by pulling the vacuum hose off and check for gas ! there should be no gas in the vacuum hose going to the regulator !

black smoke, hard starting sounds like it,s getting too much gas a flooding out ! by the pump running all the time sounds like the relay is stuck ! did you smell the oil to see if any gas is in it ? what it sounds like is it,s getting too much pressure and pushing past the injector o-rings ! the regulator,s job is to make sure there,s not too much gas or too little of gas going to the injectors !

Replaced the purge valve today,truck (so far) is running fine.Fuel pump shuts down as normal when power is applied before starting. All previous codes are cleared,but I am now getting code 542 (fuel pump circuit open;PCM to motor) I have no idea what that means. But I am happy I can drive the truck without the constant threat of whiplash as the engine cut in and out. lol

The 542 code is telling you the ground for the computer to the engine is open.
If you haven't checked all the ground connections you can find, now that is where you need to go. Remember checking them isn't just looking at them, you have to loosen them and make sure they are making good contact. Glad you solved your problem.