Engine/Transmission (1998.5 - 2002) Trouble codes 1693, 0234, 0237

[KWhitham]

I have a Dodge 2001, 2500, QC, 4x4 that has been throwing the codes, 1693, 0234, and 0237. I have a special hill that I can get the truck to throw the codes after I have the codes erased from memory. I have monitored the boost pressure and it does not get above 25 psi when the check engine light comes on. The engine only seems to throw these codes when under a specific heavy load and at or above 2100 rpm in 4th or 5th gear. The code 0237 (map sensor low voltage) is just a recent addition so I am wondering if it is time to replace the Map Sensor? Does anybody know how to check for a bad sensor or what to look for that makes the sensor malfunction? Thanks for your help!