Have that nuisance P0442 small evap leak code. Have replaced gas cap, purge valve, and purge valve vacuum canister. Didn’t help. Anyone have suggestions?

 

Do you know if the fuel pump or fuel sender has been worked on recently?
If the big "O" ring under the fuel pump access securing ring hasn't seated properly, you can get some evap errors stemming from that.

 

I had evap leaks as Mark points out, after a fuel pump replacement. In my case it was a broken plastic quick connect on the evap line to the canister close valve. I found the leak with a combo of a homemade smoke machine with UV dye and also an MQ-2 gas detector I bought on Amazon for about $3. The fix was a bit painful to do because the fuel tank had to be dropped out.

This link gives you service manual overview of the 2 places you are likely to have a problem, above the tank where the canister and valve and fittings (including the fuel pump access seal Mark mentions above) are located or at the firewall where the purge valve is.
Link

You might want to go to JagRepair TSBs and look at Jaguar Technical Bulletin XT303-03, "Evaporative System Diagnostic Flow Charts"
JagRepair

Below is a picture of my particular leak location, the failed quick connect above the tank.