The job of the PCM is to know exactly how much oxygen is in the motor at any given instant - with that knowledge, it knows how much fuel to add in order to get clean combustion.
To know how much air is in the motor, these sensors have to be working correctly: IAT, MAP, and (optionally) MAF. (The O2 sensors come into play later, in the fueling correction/trimming strategy.)
Some thoughts I would consider, in no particular order -
From what you tell me, it sounds like the truck is not being fueled correctly. I would guess it is running lean and cutting out at 4000+ rpm.
I would verify that the MAP and IAT sensors are working right, can you monitor them with your scan tool? Make sure the IAT at cold-start matches outside temp, etc. Make sure idle MAP is a sane and steady value.
Maybe you have a weak injector? A weak fuel pressure regulator? is there 52-psi measured at the fuel rail?
Cleaning the TB - this is an easy job, I would go ahead and unbolt the unit from the manifold because it's sealed with a really good reusable silicone rubber gasket, and once you get it off there you will find a crap-load of buildup in the "throat" of the manifold, behind the throttle body. But in all honesty, I don't think that a dirty TB will cause an outright misfire - my TB is *very* dirty and the symptoms it displays is the RPM taking longer to return to idle, and a racy idle at times, but never an outright rough idle or misfire.
O2's: The O2 DTC codes you have are HEATER performance - this means that the PCM sees that the O2 sensors are failing to physically get warmed-up fast enough. In trucks with aftermarket headers and/or gutted cats, this is a fact of life (cold O2 sensors) and we have to instruct the PCM to ignore these errors. But as you have factory cats, I am going to assume that you also have factory manifolds, too - which means to me that there is no reason for these O2 sensors to be failing to heat up and I would replace the front two as soon as you can afford and the rear two at your next financial opportunity. O2 sensors on these trucks should be replaced at 80K-miles anyways, I've seen several cases (including my own truck) where fuel mileage instantly got better after replacing aged O2 sensors.
The blinking light on the dash just means that the PCM sees the crankshaft slowing down i.e. it is detecting a misfire - but you already know that in the moment you are driving the truck!
I agree on using the infrared gun to verify the cats are still good, and from there check the fuel pressure regulator. I would also spend $7 and replace the fuel filter, too (it might be clogged?)