Timing Chain ?
 

2003 dodge ram 1500 4x4 4.7 engine 40,000 miles on crate engine. Replaced fuel pump...Hard start. Showed Crankshaft and camshaft sensor error. replaced both. It didn't help.. Replaced ECM, spark plugs and coil paks. Engine is showing P0016 code.. Hard to start and dies as soon as it starts. Backfires sometimes while trying to crank. Checked fuel with gauge and got 50lbs... Would appreciate any help or guidance...

Yep, think I would be checking all the alignment marks for the timing chains..... May be a tensioner broke as well.

Definitely sounds like a timing issue.
Did this problem come on gradually or suddenly?

I've been hearing a noise from the front riders side.. Sounded like a knock but would clear up when rpm increased.. Is there anyway to check and make sure I don't have a valve or piston damaged?

Compression test. After you check valve timing. :D