the 4wd switch flashes on and off in 2wd mode while driving but goes back too solid green once stopped,causes sluggish shifting,no check lights on the dash have come on either,any suggestions where too head with this would be appreciated thanks

 

Check the harness that plugs into the transfer case as corrosion or oil could have gotton into it causing a short.

Second you can ensure you are out of 4X4 then remove the switch and see if it stays locked out to rule out a electrical issue.