1995 Honda Del Sol Engine idles up and down and stalls when

This vehicle was replaced with another motor, as the original motor was stolen. However, when first started, the engine runs like hunting until the engine warms up. However, anytime gas pedal is pushed for more rpm, the engine stalls. I cleaned the IACV, cleaned the throttle body, have a good fuel pressure and spark, but still doing this stalling problem. What would cause this kind of a problem? All ideas are most welcome.