I have a 1975 Cougar XR7 that is my daily driver. I replaced the spark plugs and wires last night. I drove it about 40 miles with no issues and about 10 today. After stopping at the bank, I started it and it acted like 6 of the 8 cylinders weren't firing. I checked continuity on all 8 wires and they're good. Compression on all cylinders are in spec and the plugs all look ok. Any ideas would be appreciated.