Jd 690e troubles HELP!

ive got a john deere 690e that I have spent months trying to trouble shoot. I have multiple issues that I am trying to resolve. First off, the key switch does not work to start the machine we have to use some wires connected to the starter to start it also the electronic throttle control does not work we have to manually adjust the throttle. also when using the machine the hydraulics are real slow but sometime the hydraulics will suddenly "take off" for instance when driving it across the ground you can have the pedals all the way down and just be crawling and all of a sudden the machine will just take off. These problems basically render the machine useless unless you have a death wish. Any help would be greatly appreciated! Thanks in advance

Jd 690e troubles HELP!