stumped

i got a 90 civic with a 1.5 and i jus put the engine in, when i start it up it runs alright but when u go to drive it seems like it misses and stumbles a lot, but not always itll idle weird sometimes..the check engine lightdid come in but that was for the speed sensor{needs a speedo cable} but now the light dont come on no more, im thinkin a bad ecu, at first it seemed like a bad o2 so i stuck the one in from my old motor and no change...posibly bad also? :dunno: any suggestions...

Plugs, wires, cap, rotor.. Time for all that again maybe? :)