dashboard message reduced engine power along with a check engine light on

What is your question?

ran fine this AM, stopped at store, came out 15 mins later and get check engine with reduced engine power. Truck was running and able to get home, but ran at a little above idle RPM and no ability to accelerate. Checked air intake and that had a nest of some sort in it. Cleaned that out and no effect on check engine. Could it be a fuel problem, fuel filter?