i have a 1998 Landrover disco with the advanced evap system. Which computers will work in my truck if i look for another one? also if i hook up another computer will it work right away or will it have to be programmed?

 

What type of computer are you talking about??????????????????????????

 

the main ecu computer that is right beside the washer fluid jug and beside the charcoal canister.

 

As shown here, http://www.roverlandparts.com/discov...ne-ecus-1.aspx
there are 2 different one and once installed it will need to be reprogramed to link with the BCU and other ECU's.
What are you wanting to replace yours?

 

would it have to be programmed at a land rover dealer or could the person selling it to me program it. Mine has all kinds of water in it and my rover barely runs now. Been told its a common problem

 

No, it takes a high end scanner with Rover specific software to program the ECU.
Why haven't you removed your ECU, opened it up, cleaned and dried it?

 

Already tried that