Ford Repair: 1999 Ford Expedition Wiper Problems, windshield wipers, motor battery

Question
My windshield wipers and sprayer work fine when the key is turned to the run position but when the car is running, the wipers turn off whenever they feel like it after I am done using them. This can go on for at least a minute after turning them off. Also, the sprayer will continue spraying until I turn the car off. I have replaced the wiper relay (under the hood)and the wiper handle assembly (on the steering column) with no results. I have sense returned those items. What should I try next?   

Thanks

Answer
i don't believe in trying parts i would rather test to see what is wrong

there is several parts to this system-fuse/motor/relay/switch/gem module
could be a problem with anyone of these including fuse (have had some with loose connection in panel) but not likely-take it to someone with the tools to diagnose it, some scanners can operate items controlled by gem module once it is diagnosed if you want to perform the repairs by all means go ahead. i don't use parts stores as a borrowing place because once a part is tried it is now used and if they send me a part that has been opened or installed before i won't accept it because i don't know who/what or where the part was used a switch for example if you had a short in your wiper system and installed a new switch it could ruin it as soon as key was turned on odds are slim but it does happen. be sure and check grounds on wiper motor/battery and engine.