B16a parts and no start help needed!!

Have a 1998 Civic SI with a B16a Japan Del Sol engine (1992?).

Will not start if left sit overnight. Replaced coolant temperature sensor. No change. Seems to have spark, fuel, injector pulse etc.....

Needs distributor cap & rotor (don't think it is causing the problem) but cannot find a replacement (anyone know of where I can get one?).

Check engine light is on but SNAP-ON scanner will not communicate with car. We assume the computer was changed with engine change over.

Engine change over was a hack job and alot of things plugged off, tps does not appears to be mounted properly or correct one for car, not sure if proper computer, etc.... but car has ran fine since purchased about 1 year ago. IAC motor not plugged in (plug it in and idle surges from 1000-3000 rpm's) and not plugged idle is chugging/surging 1000 -1500 rpm.

Any help would be appreciated.

Thanks in advance

Michael