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I am having this issue right now on my personal vehicle. I am a master mechanic, but have worked on Volvos for most of that time, so Chevys are new to me. Let's start with what I know for sure, and we can piece together the rest.
1) The cat isn't clogged.
2) It's not the plugs, coils, wires, etc.
3) It sure as heck isn't the tranny.
4) It's not the MAF or MAP.
Okay, now that that's out of the way, let me tell you what it is (if you and I are actually experienceing the same problem, of course).
It's a lean condition. I'd be willing to wager that your vehicle overheats a little bit as well, especially when you really floor it and it's like this. This issue has something to do with fuel regulation.
The fuel filter is a possibility, but unless you live in Botswana (in that case, congrats on learning to write English so well), then your fuel is and always has been clean, so that's not an issue.
My guess is the fuel pump is going out, a regulator of some kind is bad,
or the signal to send fuel isn't getting where it needs to be. That
could be the cam or crank position sensor.
Another possibility is that the intake has some kind of crack in it, but this is unlikely. I tested this on my vehicle by disconnecting the MAF sensor. Doing this throws the ECU into a closed-loop, sending a set amount of fuel into the engine based on RPMs alone, not air flow. This did nothing to resolve my issue, so that's out. You can also test this by spraying brake cleaner around the intake manifold and listening for RPM spikes as the cleaner enters any cracks in the manifold.
Besides all this, I think the Colorado ECU is smart enough to compensate and eventually disregard faulty signals sent by bad sensors and leaks, given that the engine stalls. That tells me it's something mechanical and it cannot fix through software no matter what it tries, i.e., the fuel pump.
Congrats, I think we found your problem.
Source: I am an ASE Certified Master Automobile Technician
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