Random misfire code only on deceleration - 2003 Chevy Suburban

2003 Suburban 1500 2 wheel drive with 5.7 engine - not flex fuel. Check engine light starts to flash on long trips, usually about 100 miles in while driving at 75 -80 mph - RPM level of 3000-3500 . Eventually, check engine light will stay solid. If I hit the gas a little, the check engine will go out. Took to dealer and they said the misfire only occurs on deceleration and they had no idea how to fix it. Suggested a top end clean.
I have changed plugs, wires, O2 sensors to no effect.
Any thoughts?

Interesting when you lift off the gas pedal and the car is on the over run the fuel injectors normally cut off completely until the RPM drops closer to idle speed so no the cylinders are actually firing so no actual misfire should be possible. --- you have a phantom misfire
Anybody encountered this ?
I agree with cleaning the intake particularly the throttlebody and PCV but I would also check the output of the throttle postion sensor for glitches.

Codes?

Code is P0300
As an update, I can now reproduce the flashing check engine light by simply holding the RPM's at 2500. Car does not have to be moving. Starting to think this is a vacuum leak that is slowly getting larger. Does that make sense?

Any misfire data? Neighbor had a Chevy van a few years back that had a P0300 & no other codes. Misfire data showed misfires on cylinders 1 & 6 that came on at exactly 2500 rpm's. Pulled my hair out for hours & couldn't come up with anything. Everything looked perfect. He tried a crank sensor & a crank relearn & problem went away. Scoped the sensor after the replacement & it looked exactly like it did before. No explanation, but it is still running well today.

Are you feeling misfires? I was thinking along the lines as Andy about the likleyhood of misfires under fuel cut. Do you have a scan tool capable of performing a crank profile relearn?

No, I don't feel any misfire. The car seems to be running fine. I don't have a scan tool, just a code reader that uses a phone app. The crankshaft position sensor sounds like a viable target to investigate. The thing that puzzles me now is that this used to only manifest on a long trip and now I can reproduce it on demand just by revving the engine to 2500 RPM's for about 10 seconds. The check engine light will flash and then go solid if I don't immediately turn the car off. The light will go out on its own after 4-6 start cycles

Had a local shop perform the Crankshaft sensor relearn and that currently appears to have solved the problem. I'm curious as to why this would work and what the computer would have learned in the past to create this code?

Congratulations on the repair. Why it worked, I don't know. Just seems to work sometimes, when nothing else looks bad. Thank your lucky stars & move on. Hope they didn't charge you too much. With the right scanner, it's easy to do.