[Dingfodgy]

Could be a couple different things. Regarding the starter not turning over- that is an electrical issue- either with the switch, neutral safety switch, bulkhead connector or connections @ the starter itself. Get yourself a tester and start testing each connection.
The poor running is probably a combination of worn out ignition components, bad timing, clogged fuel filter, mis-adjusted float and/or vacuum leaks.
Start with one system (air, fuel or spark) and make sure all related components are in good running order.
As reliable as these trucks are- they do need a bit of time and $$ to keep going.