Hey,
I called Toyota and Scott, agreeing w/several other techs, said it could be anything from a simple pinched wire to a short in the computer. Big problem is that there so many different things wired in to the EFI comp that you'll prolly need to let a Toyota tech trace it. He said if you do it yourself BE CAREFULL! Its very easy to accidently fry the comp and its $1200 not including labor just for the replacement.
I trust these guys, Scott helped me drink beer while I worked on my Monte Carlo, he knows how capable I am with wrenching so he wouldn't try to hussle me into making an unessesary trip to the dealer.
GOOD LUCK!