i recently rebuilt the engine in my truck. its the 5.0 (305 ci) v8. in the process of rebuilding it was bored .030 over. its at the 500 mile mark and i'm getting horrible fuel economy and it spudders sometimes. what culd be causing this? would boring it .030 over effect it so much from getting 12-17 mpg before rebuilt to 8-12mpg after rebuilding? fuel filter is brand new, new copper O rings, its got me lost and i really want to have it back. somebody please help.Update:
would flashing the ecu help this?