[bnoon]

From the position you're describing, here's what I would do.

1. On full cold choke situation (i.e. sat all night, ready to start on cold morning), the flap will be all the way down once it's set (get in the cab and push the gas to the floor once). Once it's set, pure cold, don't even crank it yet... double check that the flap is now all the way closed. If not, adjust it so that it is.

2. Try to start it. Adjust high idle as needed. About a minute or two with the ignition in the on position constantly will get the choke to open some of the way. Heat from the engine warming up will open it the rest of the way.