2005 2TR-FE 2.7L RPMs Fluctuating at Idle and Loss of Power

Like the title says, I have a 2005 with the 2TR-FE engine. At idle the RPMs fluctuate almost like it is about to stall. When I drive the truck it feels like the truck is hiccuping when I give it gas. It will have the normal amount of power and then the power will drop off then pickup again.

What I know so far.

I have a P0420 engine code (I had the code before I changed the Cat and after I rest the code)
-MAF Replaced (Denso)
-O2 sensors replaced (Denso)
-Catalytic Converter Replaced (AFE)
- Coils and plugs replaced not long ago

Long Term Fuel Trim is. -15
Short Term Fuel Trim is. 2

So it thinks its running rich but I cant seem to figure out why.

I am open to any suggestions of what the cause might be.

 

New Air filter. Check PCV valve. Check Throttle body. Check Spark. Check Vacuum leak or Change hoses. There's a little known hose in the back of engine that goes into the intake manifold. It's usually ready to break in high mileage engines. Recheck for exhaust leaks but start at the exhaust manifold after removing heat shield. Since you are there, check the EGR valve and check if it opens and closes properly. There's a piece of filter foam from the secondary air pump that has a tendency to crumble and get sucked up into the EGR valve in high mileage Tacomas.