BIG loss of power

[xb visitor]

Hello, heres the issue. I have a brand new clutch with 4k on it..everything done with new parts, works great. But The car..is noticeably slower I have always been able to hit 60 in the 8.5-9 second range...now Im lucky to get under 11 seconds...Yea I know there terribly slow anyways...but now its REALLY slow.
Best way I can describe it is....It feels like its not getting any air...struggling as if going up a hill? This car has been virtually...bulletproof. Hands down the best,most durable car Ive ever owned..and Ive owned a lot of everything
.
I have a "hard" 150,000 miles over 10 years
New clutch assembly.
Doesn't use a drop of oil
Doesn't smoke
Makes no noise
Makes no smell
Throttle body cleaned.sensors
NEVER had any idiot lights or CELs...
CAI Injen intake & INGEN fireball exhaust ..both are 100% useless but each sound good.
Newer plugs, wires,air filter

Waterpump...is slowly dying it started weeping occasionally 60,000 miles ago. its making noise"sqeeking" now along with the original belt.
Its due to get replaced soon.

QUESTION: COULD IT BE THE CATALYTIC CONVERTER GOING BAD? Also has a minor loping idle? HAVE AMNY OF YOU EXPERIENCED THIS OR ANY THING SIMILAR??

[CTScott]

A plugged cat could definitely cause a significant loss of power, but when it gets that bad you will typically start seeing intermittent CELs for the O2 sensor.

Bad waterpump bearings could also be stealing some power.

[xnamerxx]

Idle issues would have me looking at the MAF or the VVTI solenoid. Both of those typically put out a code though. Your gonna have to plug a computer into it and see what its doing.

[ex-x-fire]

Maybe the fluid in the manual trans is wrong, too heavy a weight.