Q: what does the code 1404 mean on 1999 Pontiac Bonneville

Rookie cbe0621eac06868b3efe0d8d1d3611e23c60d3114864ea2ec19a68cfbd3eebab
when i am driving it it has hesitation in it while driving down the road.Have had tune-up on it and it still does it carried to advance auto parts cause the engine light came on and they check it and the code was 1404 but they could not find 1404 in their book
(1) Answer
P1404 is an EGR code.

These can be tricky to diagnose because there electric.

The first thing i would do is have it removed and cleaned.
Have someone clean the valve and the ports it mounts to.
Some mechanics will spray a little cleaner in it and reinstall it.

Spray all carbon off valve and use a small brush/pick tool and air.
Blow out ports and start vehicle with valve off will blow some
carbon out.

Cleaning valve is a 50/50 shot.
GM EGR valves average about $300.00.
Some aftermarket valve don't work.
I had good luck with used one's because the salvage yard i deal with
guarantees parts will work.