is it a misfire or fuel problem

Hi all ,well my reliable wing has started to act up on my last two outings, I usually go out every weekend and do between 150 to 200 miles, so the bike gets used, it is a 05 with 31000 miles I've put 6000 miles on it since getting it last year, 2500 on a tour of southern France with no issues
The problem feels like a misfire, at motorway speeds (70 80 mph) its like the throttle is is being shut off and opened quickly a slight stuttering and bogging down feeling but intermittently, its not the sensitive throttle action on the wing it feels more pronounced .At slower speeds the bike seems to act normally accelerates fine, starts ok and no feeling of a misfire ,but on the overrun when slowing down small backfiring seems to be happening ,
I have had the exhaust off so I've ordered a new exhaust collar gasket to see if that stops and is unrelated, its difficult to describe but its getting worse I tried the bike after checking the plugs (iridium fitted 3000miles ago) and leads which on the surface seem ok , but its still there ,that's why I was wondering about maybe a fuel problem but I suppose that would be apparent all the way through the rev range.
Has anyone else had this problem? any pointers welcome cheers k

ALL, electrical connections clean and tight?

Try testing the fuel pressure regulator? It is cheap enough to just replace it.

Did you check the air filter yet?

Hi, sounds like your ht leads when under load.

Have you tried to duplicate the problem with the bike on the center stand?

Also, you might want to remove the right side skirt and the tunnel cover. Yeah, a PITA I know but... Then some dark night do the center stand thing again while misting the coil, high tension wires and plug caps using a spray bottle of water. The idea here being to check for arcing. 

If you do find that you need new high tension wires it is best to order the correct parts from Honda. A friend was having erratic, long term problems with his ignition and a Honda shop ended up replacing his high tension wires with something from a showroom Honda (not a Silverwing) which “looked right”. Anyway, he got back on the road and the SW started acting up again. We replaced the showroom wires with the correct SW ones. Dunno what/why the difference in wires, but all was well and he lived happily ever after.

Try purging the fuel lines of fuel near the injectors, its in the manual. I had a similar issue where the bike eventually would not start, 18 years of use had pushed fuel resembling mirky home made cider up to the injectors and prevented the clear amber nectar from reaching the bores. Check my past posts. The SW has to be the most complicated engine I have owned, lots of sensors to potentially cause a issue but Honda know how to build a bike so only the one issue in 20K miles so far!

Sounds like a misfire. You had the muffler off or the head pipes also??? A leak at head pipes would cause the popping in exhaust. Pipe gaskets are a crush type and only one time use.

Fuel is leanest at a steady speed this is when a misfire is mostly felt. Accelerating it has more fuel and a weak plug or wire will still work until it leans out.

Purge WHAT? Fuel system has a return to tank it's flowing at all times engine is running. Only problem I could see if pump or fuel system opened then a few cycles of key would pressurize system no bleeding required. You had lots of water-bad fuel in tank.

I can't comment on the motorway speed misfire but I get a some popping when shutting off the throttle (sometimes). I've mentioned before that a new air filter and plugs stops it from happening for a while but really, I've never worried about it. The bike seems to run fine otherwise.

Tim's suggestion regarding the plug leads and caps is worth investigating for starters.

I'm going to give my SW a shot of Redex on the next service and check the plug leads and caps too!

Thanks for all the replies ,the plug leads will be my first port of call probably get some new ones.
Seeing as the Costa del Liverpool is now under new lockdown I'll have plenty of time to fiddle about with the wing:)