ok, need to know what kind of motor for one. on your aftermarket TB, does it have a spot for the map on top? if so, thats where it needs to go. that eliminates the vacuum hose coming from the TB is all. what you need to do is borrow a vacuum pump, apply vacuum to the map sensor while monitoring the signal voltage coming from the sensor, should be between 1.0-1.5v at idle (high vacuum) to 4.0-4.5v (low vacuum) at WOT. also check power to the sensor, should be 5v. (or you could just try replacing the map with a known good one to avoid all that). if the map sensor voltage is good, and the signal voltage is good, there might be a problem with the TB? but testing the map is what i would do, cause a code 3 and a code 5 is basically the same, its a problem with the map sensor circuit. let us know what you find...