Got an 85 mustang gt automatic. I recently noticed on the highway around 65mph around 2k rpm, my rpm gauge will stutter and the car with jolt quickly like a misfire. It did it about 10 times in 15 seconds yesterday. I then made sure my spark wires were routed correctly (1 and 3 far apart, 5 and 6 far apart). That greatly improved the issue. Now on highway, it only does it once or twice every few minutes. I replaced the spark wires, ignition coil, distributor cap, distributor rotor today trying to fix it but that stuff didn’t help. It still does it once or twice every few minutes. Very subtle and you might not notice unless you’re looking at rpm gauge the whole time. What else could this be?