Well - I took the Crossfire into the local MB dealer yesterday. They still insisted that a full diagnostic be done but I also insisted that my crossfire forum buddies had said that it was just probably low on ATF so they concurred and did a level check and fluid change with new filter,seals etc.
I was a bit worried that it was something more ominous but when i picked the car up the gear shift lag had disappeared and all was at it should be.
I did give the battery a good charge as 'pct' had suggested but this made no difference. Also I checked and confirmed that i was indeed in summer mode
Waiting now for the sun to come out in the UK - Wimbledon tennis next week so that usually guarantees unsettled weather.
Back to Florida in October for the winter - wish i could take the crossfire with me
Thanks to all those who corresponded
regards
Richard