ECU swap questions

[Silverstreek]

ok, trying to figure this out. i bought another ecu recently that i plan to send off to have nistune installed on. i just got the ecu in the mail yesterday and want to be sure it's a good ecu. so i just went out, disconnected the harness going into my stock ecu and plugged it into the used ecu i bought. connect the battery, fired the car up and it ran like i had cams in it. kinda looked like it was a little bit rich (smelled like it too), but mainly just ran rough. disconnected the battery, disconnected the harness from the used ecu and reconnected it to my stock ecu, reconnected the battery, fired the car up and it runs just fine.

i'm just wondering if the ecu needs to be all bolted down in the car in it's location? maybe there's a ground or something there and it needs to be bolted down, cause i didn't bolt it down? it's a 92 ka24de 5spd and the ecu i bought is supposed to be from a 93 ka24de 5spd (even though lookin at the p/n shows it's from 91). the ecu case doesn't look damaged or anything, don't hear anything rattling around inside. really the only difference i see is the green and white sticker at the corner has a different number than my stock ecu (mine has a 30 on it and the used one has 24 on it). i know a auto ecu works with a 5spd car, but not visa versa, so that shouldn't matter. do the regulations, as in if it's a federal or california car, matter for anything? my ecu p/n says my ecu is a california reg, whereas this used one says federal reg.

i'm gonna go back out and take my stock ecu out and bolt this used one down like the stock ecu is now and try it again, but thought i'd ask and maybe have an answer if i try again and it still doesn't work.