84 full size K5. 350, manual transmission. Driving in 1st gear is fine. Shift to second and if I step on it just a little, it stumbles until I get going faster. Same with 3rd gear. Stumbles. Cruising speed, step on it and it'll stumble until I get moving faster then it idles out. Timing is 4 degrees. New wires, cap and rotor are on the way. For now, the cap, rotor and wires have to do. They are three years old. I did remove the cap and rotor and sanded down the carbon off the metal tips. Still stumbles. Carb seems OK. Starts up in the morning fine, chokes seems to be working fine also. Ideas? Thanks!