[68 P.O.S.]

Why do you still have the TCS connected, and does it actually work still?? If it works, and correctly, it's not allowing the vac advance to come in just yet as designed. I would disconnect it and remove the wiring; it was an early, crude emissions thing and it provides no benefit to your engine and only stops your vac advance from working correctly. The only people who really still use the TCS are those doing a factory correct restore, or they just don't understand the TCS. Plug your vac advance can directly to manifold vac and you should see the idle increase. If not, you have a bad vac can. Now you need to find out how many degrees of advance your vac can provides. You want it to be around 10 degrees, or you'll probably get pinging if it has more than that.