1989 Chevy Cheyenne Wont Start

My husbands 89 chevy work truck gave out the other day and he cant figure out what is wrong with it. It kept bogging out but would not completly die out. (kind of like when your running out of gas) First it didnt have spark coming out of the distributer so he replaced the pick-up coil, ignition modual, distributer cap and the rotor button but it still wont start, even though it now has spark. And I should tell you it has gas and theres gas going into the carb and spark plugs. Any Ideas?? We need help ASAP!!

Spark is not happening at the right time,no compression.Theres an answer for you.

If the compression is low then the timing chain may have slipped.

Thanks we’ll try that next!

OUCH!!! We just found out the block on the truck is CRACKED! No wonder it would not start!
Thanks for all your help guys. Looks like were buying a new motor!