Hi all. I figured I'd reach out on my problem if it's something that's already been solved feel free to send a link. So I have an 07 equinox about to hit 170k, I recently changed the spark plugs, wires and injector 4. All of this because it was loading power more and more, even after doing this it still says misfire on 4. Yes it was a rebuilt injector, I just can't believe the odds of getting a bad one. A bit of explanation, but losing power I mean flooring it on a straightaway and it hitting 3-4 rpm and inching up to 40 mph. I look forward to any help you'd like to give me. Thank you all and God bless.
~Joshua

 

Maybe tranny slipping if you are getting those rpm's??

 

It seems to shift fine but acts like it's running on fumes.

 

After changing the spark and injector you can try swapping them with another cylinder. If the misfires stay with #4 there is only one possibility — mechanical. Rings, valves, head gasket are all suspects. A compression & leak-down test on that cylinder can confirm and a skilled mechanic will be able to tell which is causing the problem. Other possibilities for low power include a plugged converter, un-metered air in the intake and ... informed testing beats guessing and parts cannon every time so pay for a diagnostic at a trusted shop if you have to.