92 Capri 1.6L DOHC non turbo hesitation / backfire on touch of throttle, poor acceleration

Have done all diagnostics and checked or replaced many parts and everything checks out fine, only thing that seems to work is to set timing at 12 to 14 deg BTDC which eliminates hesitation but acceleration still not perfect. Makes me think cam timing is out but checked it by removing top cam cover and setting on 0 deg TDC on compression stroke and cam marks line up, at a loss with this problem.