Help us help you. By posting the year, make, model and engine near the beginning of your help request, followed by the symptoms (no start, high idle, misfire etc.) Along with any prevalent Diagnostic Trouble Codes, aka DTCs, other forum members will be able to help you get to a solution more quickly and easily!
Do you have any fault codes or other symptoms to go along with your fuel trims? +11-15% isn't ideal, but not terrible, either.
Definitely post a screenshot of your injector ramps, if possible. For whatever it's worth, the injectors on the 3.5L/4.2L engines have historically been very reliable. Can't recall replacing one. Unlike in the shorted injector video, your Colorado uses sequential fuel injection, with each injector having its own driver. One shorted injector won't disrupt the function of the others in the same way.
Better fuel trims off idle would tend to suggest that fuel pressure is fine. If you wanted more confirmation, you could always check for power enrichment at wide open throttle. If you see the upstream O2 show full rich at wide open from a stop to the 1-2 shift point, then it's unlikely that you have a fuel delivery issues (pressure or injectors).
Off topic, but did you use the 'Private message' tab to create this thread? If so, just use the normal 'Message' tab in your reply. The private function may make your message invisible to other members, and makes it difficult to quote when replying to you.
Only code is P0420. I found that exhaust manifold has hairline cracks. Cleaned area and put extreme heat jb weld. Did not fix fuel trims but did fix the issues of idle problem truck had after sitting overnight or for a long period. Sounded like truck had a racing cam. Now it sounds fine and normal. Do you know if timing chain slack affects fuel trims?
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