I have an 05 ss sc 114xx most of the time i can not bost over 8psi i pull a good vacume but hardly no boost. On some days we will randomly boost 12 and over but then just goes back to next to nothing. Just recently replaced mass air flow sensor and 02 sensor because I had engine code for them I pulled throttle body off and cleaned. Will the by-pass valve be the cause of this?

 

Mods?

 

Pretty sure mostly stock becides cold air intake and exhaust

 

WD40 the rod on the Bypass Valve it's rusted