[Alan Lindquist]

1980 SC. At first I thought that my clutch was slipping. I did the 5th gear pull from 25 mph and there's no slipping. Clutch is a Sachs with less than 25,000 miles.

Perfect idle. Revs in neutral are clean and crisp. But when driving (in any gear) the engine seems to bog and hesitate and stumble under load.

It's been raining a lot. Could be a bad tank of gas. Could be bad timing. Could be clogged fuel filter. Could be poor spark. I have a "tired" fuel pressure regulator that causes rev surge in cold temps, and I haven't put the pressure gauge on to confirm pressures, but other than idle, the engine runs strong when when ambient temps are > 50 degrees.

Have an 8 month old rebuilt Bosch ignition box, 18,000 mile Bosch plugs, 120,000 mile+ ignition (shielded) wires. Cap and rotor look "ok" but not fresh.

Where's a good place to start?

This is a daily driver with 250,000 miles on the motor.