Serious Problem

I got a 91 Mr2 2.2, replaced engine with import 30-to50k. Had it all put in and everything, but after the switch the car was much slower, and shooting flames out of the exhaust, I cant get it to stop running rich, its burning gas like crazy, and blowing thick black smoke.. the car also bogs out when u get to about 1300 to 1400 rpm some please tell me what could be wrong, i have replaced map sensor as well.. thanks

i thought the 91 na was still a MAF sensor...

The NAs do not have a MAF/AFM.

How old are the ignition components?

did you use the wiering harness from the usdm engine? ecu? sounds to me like you used the map from the jm engine and the harness from the usdm maf...or vice versa

30to 50k which is what?