Help won't start

Got in the truck the other day and would only click, had it towed home and replaced the starter and battery, when it started it sounded like a diesel and died, now it cranks fine but won't start and if it does it sounds like a diesel again and runs really rough and dies. Not sure which direction to go in now.

broken cassette guide?

If you have the SOHC V6 and over 150K miles on the odometer then one of your cassette guides may have broken. The only way to tell for sure is to pull the valve covers and inspect or pull the lower oil pan and look for parts.