Most QC's feel that way . Did you happen to start noticing it when you got the Viper? If so, I think I know the problem. Let me come get the car (I'll have to take the seat out, but I'll keep all the bolts for ya) and your truck will start to feel fast again in no time.Mine has been slow for a long time now.
Replaced plugs and wires and installed demon coils... no change
Cleaned out intake manifold...no change
Cleaned injectors... no change
Built a true CAI....no change
Bought a JTSVP TB.... no change, except have a surging idle now (still)
Bought new TPS and IAC.... no change...
Installed B&B long tube headers... with high flow cats.... a little improvement.
I don't know what else it could be other then maybe the engine is just tired.
My truck feels like its 50-75hp low.