Hi Jeff,
I wasn't sure if you'd arrived at a solution to your problem, so thought I'd ask a few questions. I looked over your code, and didn't find anything obviously wrong, though I'd encourage you to name P1.0, etc with their uses (DIN, CS, etc...) using EQU assembler statements, then use those in your bit banging code for readability. One question I have is if you drive the ADC continuously for a given channel, and look at the ADCs SSTRB pin (From Max datasheet, as I couldn't find a TI0838) and it DIN pin with an oscilloscope, does it go high following the Command byte each time as it shown in Fig12a of datasheet? I also wonder whether the input you read from any channel is an AC input, or a DC input? In other words, if you feed a 100Hz sinewave into any channel, is it converted, or are you just getting a constant DC output from the ADC which may not be linked to any input? Hopefully you have already solved this, but if not, I hope this might help.
Best Regards,
Josh Morong