[HO455]

Asto the OP's question. To check the timing advance hook up a timing light and while looking at the timing mark on the balancer rev the engine up. The mark should move about an inch. This the very basic test to see if the mechanical advance is working. For more detailed information there are dozens of videos and other articles on the interweb that detail how to set the timing properly.

On the fuel side a quick and easy check would be to remove the gas cap and do a test run. That would tell you if your tank isn't vented properly.

You didnt mention what year or how modified your truck is. That information may help us troubleshoot.

Also any rubber hose between the fuel pump and the tank should be checked to see if it has collapsed. If it looks flat it may be collapsing and restricting flow to the fuel pump.

Good luck and keep us posted on what you discover.