Ok so to start from the beginning, I bought this truck from a old man it sat for 2 years and he replaced everything to get it running and driving. Well I got it for 800$ and it has 126k miles, automatic transmission, and 2wd. The engine is the 4.9 300 straight 6. So the day I bought it, it started overheating real bad ended up being the T joint that runs from the fire wall to the water pump and then in the middle, to the radiator. Anyways I ended up buying a new thermostat, radiator 2 3/8", and a water pump. The next problem which I already knew about but everyone told me this truck was "bulletproof" was when I shifted into reverse there was like this big bang noise and then under the bench seat a deathly rattle but if you gave it throttle it would go away or if you shifted to a different gear. So that was fine it all ran well and worked. Well it did have a check engine light on and i ran it and it was code 628 excessive clutch converter slippage. So I drove it for about a month and everything was fine. Well then one day I was driving above 60 miles per hour and it stalled so for a couple weeks I couldn't drive over 60 miles per hour or it would stall. Slowly over time it work down to 55 miles per hour than 50 and then one day I couldn't go over 25 miles per hour without it stalling, when it stalled it was like it ran out of gas, it sputtered and and then the engine shut off and once it did the deftly rattle would happen again for 1-3 seconds. So I end up checking the fuel filter and it was full of rust so I replaced it that did not fix the problem. Well I let it sit for another day and came back today and started it and drove it to my house and whenever it would shift into 1st 2nd and 3rd gear it would Lurch forward and it always did that when I put it in drive but now it's doing it only first second third year and that's only from where I do it from Park to drive if I do it from drive to first gear or second gear does not lurch. Also I noticed on the way back from my house back to the shop that if I turn on the headlights the truck stalls no I did take the grill out in the grill piece around the headlights on both sides so that maybe a short or something that I made I mistake on. So pretty much I want to know what the rattle is, also why it is stalling or what could it be and last but not least why the headlights would cause it to stall if I turn on the the main beams (wont stall on fogs) anyways thank you for your help.

 

On the headlight issue check just in front of the battery, there is a stud on the inner wall of the engine compartment with a ground wire that should be attached to it. Take it apart and clean it and see if that fixes it.

As for your other issue I am not sure, but just a wild stab in the dark, sounds like you smoked your transmission. What type of tranny have you got? When people refer to the truck being bullet proof, the are most generally referring to the engine. I also have a 93 with the 300 I6 and an E4OD. both engine and transmission are working fine.

 

Sounds like a fuel problem.
Put a fuel gauge on it and check the fuel pressure.
You may also have a charging and/or battery problem.
Low voltage could also drop the fuel pressure and cause the deathly rattle (lean knock) along with speed restrictions.