running problems.

i have a 92 eagle talon tsi. and after a trip to NH from mass the car started running extremely rich and there were 2 codes. i looked them up and it was the baro sensor and the IAT sensor. so i replaced the air metering assembly and it still runs like crap and still has the same codes. also one minute wit will run fine and the light wont come on, and then later it will come on and start running extremely rich, and some days it wont. so i got a ecm off ebay out of a 91 tsi, and when i put it in the car cranks but wont start, and also the check engine light does not come on for a second when the key is on. wich it should. any ideas?