Recently changed the MAF Sensor on my 2003 Silverado 1500HD 4X4. Not setting any more codes but now the car is chugging/sputtering during light acceleration. Any possible causes. No answer from mechanic.

have you checked for any vacuum leaks?
do you have a scan tool?

Use a fuel pressure gauge and post the fuel "PSI" readings? Last time fuel filter was changed? Last time plugs and ignition cables were changed? If you're gonna change them you gotta use A/C Delco plugs and wires. Don't use anything else.

just what was the code number?

Let us know exactly what code or codes are set. Here are the most common ones for the problem you are describing.

P0101
P0102
P0171
P0174

check the vacuum line to the MAF (especially where it comes from the engine).
Generally, changing the MAF wouldn't cause this problem so check for anything that may have been disconnected by accident.

check that PCV hose and spark plug wires on that side of the engine (actually both sides--was just thinking that maybe something on that side got disconnected during the repair).