Thanks for responding, I can only see kpa with my scanner. When I unplug my map sensor the kpa drops to like 5 or 10 kpa. What color is the map wire and do you know which connector red or blue. Thanks

 

HP Tuners can log the MAP voltage, you just need to pick that specific channel to view.

https://www.lt1swap.com/gen3_schematics.htm

https://www.lt1swap.com/99-02_vortec_pcm.htm

 

Possible gross intake leak? You can check MAF flow rate and IAC position compared to a pre-headjob scan to see if both are bottomed out. It is a stretch as a leak causing a true 102kpa manifold vacuum would idle really high but the low MAF reading may prevent enough fuel to rpm, thus the popping and rough idle.