Have you driven around with it yet?
I don't mean using it as a "poor mans cruise control", but just normal driving?
When I 1st hooked mine up to the throttle body, it would/could interfere with the gas pedal. The engine would sometimes, NOT return to idle, but race a bit.
It did that randomly/ intermittently until I went to home depot and got that little gray thing that hooks to the throttle(in the 2nd pic above). I also had to epoxy the end of the black housing for the cable into the adjusting ferule it goes into in my pic 3 above. Otherwise the slack in the cable when I press the gas pedal would bugger things up a bit, and the engine would race a bit.
Just a heads up...
Jeepster93 has a good point here. I installed a setup almost exactly the same as yours and it worked great for a while but every once in a while not allow the jeep to return to idle. Its not the end of the world as normally just revving with the hand throttle would free it up. Only once did I actually have to get out and take the cable off the throttle body because it would not drop lower than 2500 rpm's.
A suggestion for anyone considering this project- instead of WD40 or grease use mountain bike cable lube from a bike shop. WD40 and grease will make it slippery to start with but get gunked up quickly inside the cable housing and could cause more problems in the end.
All in all a great write up though!
91 wrangler 4.0L, 4 in Suspension lift, 1 inch Shackle Lift, 1 inch Body Lift, 35" BFG Mud Terrains, Warn Rockcrawler Front Bumper, Hand Throttle, HiLift, 12 pack of Natty Boh.