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Discussion Starter #1
2009 4.0l, 245k miles. Only 'mods' is a throttle body spacer and screaming demon coilpack. The car has been for the last few weeks being sluggish on the higher end rpm. When the car gets around 3-4k rpm in all gears it acts like the governor is kicking in not letting go higher wether soft or hard on the pedal. I have recently (in the last 2 weeks) replaced the water pump.
In the last 3 days I've replaced bank 1 sensor 1 02 sensor (car was getting P0420 for several months but acted normal) as well as fuel filter. However, car is still having same Acceleration issues in all gears.
 

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Sorry for the late response. This website doesn't regularly provide me with e-mail notifications any longer.

I would begin the diagnosis process by doing a fuel pressure test to try to narrow down the possible causes, in the absence of any diagnostic trouble codes.
Also, if you haven't already done so, pull out the spark plugs and make sure that they all look normal and are in good condition.
And you might clean the Mass Airflow sensor and the throttle body if it hasn't been done.
Basically, start doing an old fashion diagnosis, checking all of the tune up items, inspecting for vacuum leaks, etc.
 

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Discussion Starter #5
I also forgot to update, P0420 came back 2 days ago, still reading sensor 1 bank 1. At this point I'm leaning towards catalytic converter
 

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That would be the most likely suspect at this point.
I had one break apart on the inside a while back. That was easily diagnosed by the horrible rattling and banging sound it was making at idle.

Well, good luck!
Post an update if you get a chance.
:thumb:
 
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