I changed all fluids, the distributor cap, rotor, spark plugs, spark plug wires, and now my 164 won't start unless I leave my foot on the accelerator. I triple checked every hose and all were attached and without holes. Jump starting doesn't help. I did notice that the throttle linkage seemed a little loose, but maybe that's normal. Any ideas?

You have an idle speed adjuster between the two hoses connected
to the auxiliary air valve, just outboard of #1 injector where you
can speed the idle up. If you adjusted the ignition timing, or changed the
points without adjusting the timing, that will affect the idle speed,
so be sure your ignition timing is set right.
--
George Downs, The "original" Walrus3, Bartlesville, Oklahoma

How loose is a little loose? There should be virtually no play in the linkage. When you press down on the accelerator pedal you change the settings on the throttle switch. The throttle switch is located side of air intake into the intake manifold. There are 4 wires that go into the connector. Don't take the switch apart unless you know what your doing. The settings can get messed up and you may have bigger problems. Check the connector clean the contacts and make sure all wires are making good contact.

Normally you would not touch the accelerator pedal and just turn the key on and let the motor start, but this not appear to be the case. Anyhow try the connector and see what happens. Good Luck.