Kickdown Adjustment

A few weeks ago I developed a bad exhaust leak while driving down to college in Charleston, SC. I got the manifold gasket replaced and a few other things replaced as well. The mechanic put on a metal shim between the two manifolds where they connect by the heat riser, and put on a larger base gasket for the Carburetor. Everything runs fine except when I go to cold start the car and when I'm braking.

I have checked every possible thing (choke, mixture, idle) everything. I'm hitting myself over the head for not realizing the bigger gasket and shim put the kickdown linkage out of adjustment.

I don't have a workbench or power tools as I go to a Military College. Just the tools in my trunk. How can I re adjust my kickdown linkage so that my car can better cold - start and not BANG when stopping at a stoplight in Charleston?

Thank you!