Running lean

ok so ive been running lean for awhile now. It started right after intake manifold installation. Any suggestions?

What intake? LS6? Other mods? You probably could use a tune.

My aftermarket maf caused lean codes until i put the stock one back on. The factory tune will not allow much room before throwing a code.

I would think something isn'e sealed up so you're getting unmetered air in the engine. If the air comes from anywhere other than through the maf, the car won't add fuel to compensate for the extra air and you'll go lean

i know i need a tune, but im waiting until i get my exhaust installed. I was just wondering if anyone else had any problems with aftermarket intake manifolds not sealing correctly.

have you checked for any leaks?