I recently removed the stock engine from my 1994 90Q which I am assuming was an AAH and I swapped in a V6 from a 1995 90Q which I am assuming is an AFC. The engine will start but wont rev over 2,000RPM and you have to be able 1/2 throttle to get an idle. It smells rich and the plugs go black quick. I am trying to figure out if there were any changes between the two engines that would cause it to not run right?

I went from an AFC in my wife's '96 A4 to an AAH from a 94' 90 and had no issues. I did however only use the AAH as a long block and replaced the intake, exhaust and all of the sensors on the engine.