help very rough idle

[Octanerush]

got a question here. i have a 94 svx

for a while when it gets really cold my car would start but idle like it's runnin on 2 cyl. i can smell a lot of gas not getting burned

so i tried almost everything tps, ecu, maf, water temp, etc etc i gave up and bought another engine with 80 K from a place that imports em from japan

so after i dropped in the engine did valve cover gaskets rear main seals etc to prevent future oil leaks.,.and regular maintance things like oil change spark plug fuel filter etc

anyways car was running fine for the last month until recently i had some stalling issues which come and go

and now it's now starting properly again. i crank crank it would start run like ****. i give it some gas it stalls. crank crank it starts runs like crap i give it gas and once it passes the 2-3k range it would run fine and then back to idleing fine and afterwards if i turn it off and start again it would run fine

and it seems to happen so randomly. like today it started fine and down the street i try to gun it to make a light and it would cut out and barely make it pass the light it would stall and when i try to start it it would run like crap and after some gas + crank it would be fine again

any ideas???