timing ???

i need some help here with my timing .... i dunno where to time it cuz one of my friends changed it when i did my motor swap.... how do i know ? or figure it out ... just do it by ear ? im cluelesss with this stuff so please help my motor is running like its stock

gt 40 upper and lower
trickflow twh
1.7 rr
b303 cam
24lb inj

also could there be a problem with my mass air ?
this motor came out of an 88 and had the mass air conversion in the computer
i put the motor in an 89 and used a a9L computer could sumtin be screwed up here ? the motor feel sluggish

i think it is its all from the other car the motor came from and was running with.... what do u mean pull codes ?