After much reading about the F-L switch table I finally cracked it.
All the very slow to get down to normal idle speed was purely down to the F-L switch table.
I forget exactly where I read the info from Wayne at Power Tripp, think it was on Triumph Rat forum, but he and another explained very well what I initially expected. I'm no expert, but on the tune the fuelling is pretty high and where the F-L switch takes place on the first map I tried from about 1900 rpm to about 3800 rpm, is at position 22-31. Now, I followed Waynes suggestion to reduce the crossover point if you like to position 3 in the 4 fields from 1910 rpm to 3700 rpm. It worked a treat!
The bike runs as smooth as a hot knife through butter, seriously, it's now a delight to drive. There's no snatchiness down low, feels just rich enough, is wonderfully smooth, the decel popping has gone and instead, there is a beautiful low rumbling gurgle, it's just amazing! I had now found new love for the beast. I new there was a fix for my problem. Maybe those original F-L setting were to compensate for O2 sensor adjustments, not sure. All I can say is it might work for you!
Thanks, Wayne, from Power Tripp, you are a god!