[Grady Clay]

Harry,

Stop driving until you confirm both cams are in time. One cam out of time or stopped can make the engine feel even less than a 4-cylinder Pinto - in fact it is running on three cylinders. There can be many other less complicated reasons for the lack of power but driving a 911 with a cam out of time can lead to a destroyed engine.

The easy test is to measure the cranking compression. This test is worthwhile in its own right to establish proper engine condition.

Other simple reasons can be ignition out of time or points closing up. Is the tach operating normally?

Have you measured the fuel pressure while driving?

Did the throttle cushion brake? It is a little, round device above the transmission mount. Check for full throttle.

EDIT:
Take a hair dryer to the cap and ignition wires. (Do not do this if ANY fuel vapors are present.) The moisture may be the culprit. If in doubt, replace the cap, wires and plug connectors - good annual service in any case.

Are you sure that the performance changed when you changed the filter? I'll again want to know the fuel pressure while driving. Measure the fuel flow, open circuit with a hose back to the fuel gas cap.

Best,
Grady