Steve,
I connected a simple bicycle brake lever to the gas pedal / factory hand throttle prior to the stampede this year. This has helped me with control since I went to the ZF5. The price was right at $10 bucks.
As you, I'm running the Ford EFI. This set-up works well, but has a slower throttel response time than I'm used too.
I had to learned how to anticipate throttle timing a little bit more. But, I definitely have more control in the slower technical wheeling by using it.
I have keys in hand if you want to try it first. Just let me know.