[fanaudical]

Confirmed that throttle linkage is not sloppy. Motor/trans mounts are new with the rebuild. I tried to shake the engine around just to make sure that nothing is moving and all seems tight. Ignition is good (don't see any issues with erratic timing or advance).

Bucking is there at lower rpm/low throttle right from cold. I warmed up the car and then disconnected/plugged vac line to the decel valve with no improvement. I reconnected decel valve vac line and then disconnected/plugged vac line to the WUR - and that made almost all the bucking go away. It also made it seem like the decel valve got adjusted (more "hang time" on rpms). I verified the decel valve diaphragm is intact.

Check my thinking here:

Disconnecting my vac line to the WUR essentially reduces control pressure and enriches the mixture. For that to help, I must have extra air getting in someplace (i.e. vac leak that I haven't found). The bucking I'm experiencing at part-throttle is a too-lean condition because I've got air bypassing the air flow sensor (which also negates an issue with the decel valve bypass circuit, as all that air goes past the air flow sensor).

Sound right?