Something is amiss with the Mass Air Flow sensor . . . found this on a Corvette site . . .thinking our 5.3 should be similar. . .
P0102 MAF Low Frequency
Page 6-1416 of 2K manual
This DTC is set when PCM reads too low an airflow thru MAF as based on information from other sensors, and is set when engine is running, battery is charged (greater than 8 volts), and the MAF shows less than 10Hz for more than 1 second, on the second consecutive occurance. Both these codes will clear after 3 NON- consecutive aperance of the above conditions.
First inspect for a vacuum leak, a PCV leak, a bad PCV valve, dipstick or oil cap not tight.
1. Inspect all MAF and PCM connections for debris or damage.
2, With engine idling, and a scan tool, confirm MAF is below 10Hz. If so, check ENG SEN fuse, and then confirm for 5V at MAF signal wire and ground. If OK, continue below. IF MAF is above 10Hz, there has got to be an intake of unmetered air - see above, and also inspect ALL intake components.
3. Check for all continuity on MAF wiring between PCM and also to grounds, as indicated by schematics.
4. Replace MAF sensor.
5. Replace PCM.
You can certainly look for loose vacuum hoses and / or electrical connectors . . then, unless you have an OBDII scanner, it's probably off to the shop.