I have read many a post about where the vacuum advance line gets connected to and almost all the responses offer different opinions it seems. Concerning my 84 K5; 84 Q-jet on a 350. When I hooked up a vacuum gauge to the ports, only one port has vacuum. Three small ports on the front of this carb, two on either side of the carb at the base and one toward the top of the carb. The two ports at the base of the carb have no vacuum at idle. The upper port has vacuum at idle which is where I connected the vacuum advance line to. Someone mentioned to me "don't connect it their, that's full time idle." Another person tells me, you want full time idle. What gives? Running problems? Well, sort of. Manual transmission. Granny gear and 1st, 2nd and 3rd. If I drive in 3rd gear around 40 MPH, the engine stumbles. Speed up to over 55 and into 3rd gear she goes and runs fine. The same with 2nd gear, below 30 MPH or so and it stumbles. Never did this before until last week. What did I do or change? Nothing! Just the gremlins taking over it seems! So, I'm thinking that full time vacuum might be causing the problem.... but the other tow ports don't have vacuum at idle. So, any ideas? Let it remain connected to the vacuum at idle port? Timing is 8 degrees.