3.4L seems slow after 3000rpm

Where to start?
I shift at 3k or before because there is nothing after... more noise and no real go.. almost feels like a turbo motor that fell on its face

I tried to find some dynos and found a few tid bits mentioning

190hp@4800rpm
220lbs.ft@3600

Is this power loss/cutoff normal for the 3.4L?

I was going to start with the fuel filter and MAF
Plugs look new, already seafoamed a couple months ago
Just screwed deck plate mod back in (didnt really drive the truck without it ever)

My exhaust is not stock and i dont know what it is, not leaking/rusted though

Any input?
Where do you start losing power?

Thank you much

 

hmm thats where i start gaining power or so it seems id keep the deck plate out for now if i were you but exhaust sounds like it would help at 3k rpms maybe clogged cat or something of the sort maybe someone else could chime in

 

I put the deck plate back in and it seems ok above 3k again

Thanks for the input its something to look at.. im gonna try to reset the ECU and take out the deck plate again to see if it can adjust accordingly, but its a releif and weird that i got my power back with the plate back in

 

yeah that does sound kind of funny maybe there is a problem with your injectors if more air isnt helping or something like that. if theres more air and less power it could be running lean i believe reading up on gadgets site about how at high rpms his supercharger would feather out and he replaced his injectors or something like that