1993 Chevrolet Truck • 140,000 miles

1993 Chevy C1500 5.7ltr 350. I recently changed the fuel line, intake gasket, and throttle body gasket. Truck ran fine before the intake gasket was replaced. Now its using A LOT of fuel and it gets a check engine light only when sitting still for over 2 minutes. Also is now very sluggish when pressing the throttle. All Vaccumes and sencors are reconected, I haven't seen any leaking of gaskets or fuel. What else could it be?
June 25, 2011.

I have been having a similar problem. If I step down on the throttle pretty hard it will kind of sputter and it will not excel orate. If I ease into the throttle I can climb to a decent speed but I cant climb hill very well at all. I replaced the Catalytic converter and air filter and it still has not worked correctly. Please let me know if anybody knows what this is?