Need help, ive tried everything, please!

[cfish462]

I purchased a we4 about a year ago, i restored and im now selling it. I found a buyer and all of a sudden the car acts wierd; it boosts up until maybe 20 mph and falls flat on its face. no boost, maybe even less rpm. the check engine light came on as well. i cheched it and i got code 42: malfuction in the electronic spark timing system. Has anyone had this problem, howd you fix it? gnttype.org said some possible causes are grounded bypass or est line. which are these? any help is appreciated, thanks.

 

[onefastcar]

est module is on the passenger side firewall, a black box bout 2x2" check that the connections are not corroded i think its a 4 wire connector going in through the bottom and trace the wires and make sure they are good.