1989 Chevy Camaro timing

Hello, well my car has a timing problem, well before it wouldnt start it wold crank but not start. So I new it was a timing problem cuz it ran before but not gettin full power so at this point it does not want to start, but it cranks like it wants to start. So we set the timing maualy by taking the crank pully off and set tha came timing and the chain, we set the chain and it started. But when I try to drive it cuts back off you can hear it off time a little bit. Another mechanic said it still off time. So should I use a timing light to set it or what?