I re-installed the Grecom Digital Interface to include the cpu etc. The only delay I can see available under "General Settings" over in the right-hand column and that's referring to Priority Settings and delay, which it appears the default there is 2.0 seconds.
Might be interesting to load up the Whistler EZ Scan and then dump your configuration etc. from the PSR 800 into the Whistler EZ Scan and then use that setting under the trunk area for delay you want and test the scanner to see if it applied.
ADDIT: I found your delay and most like what you saw in the past - if you pull up one (individual) scan list you will see "Dly" - it's the seventh column going from left to right. You can set the delay for each individual station you have in a particular scan list.
I just tried from the keyboard. Couldn't find it. I assume it has to be done from ezscan. I could swear you could change the delay time from the scanner itself. There has to be a way if I figure it out I will post it.