A '33' is NOT necessarily a MAP sensor gone bad. What it means is that the MAP is reading intake vacuum (inches Hg) too high (absolute pressure too low) for a given engine RPM and throttle angle. There are many other things which can set a '33' aside from the MAP sensor itself.
In the place of an AutoXRay, try to borrow a Snap On MT2500 to communicate with the ECM. You'll need a MT2500-1097-up or an older model specific cartridge, the MT2500-10 (GM-1) DLC Adapter, and the cable.