the thermo valve likes to stick with corrosion over time. pull it and polish the piston and bore to get the idle to stabilize. as for the wur don't remove it since it modulates the control pressure based on coolant temp manifold pressure and baro pressure. you can make it easily field adjustable by replacing the diaphragm pin with a machine screw but don't forget to put a non hardening sealer on the screw before install. your control pressures are something i might be interested in checking out as well id have to look up what the spec is for an early 450 but off the top of my head its somewhere between 25 and 32 psi lower pressure make for a richer mixture. and finally check the mixture at each individual cylinder with an ir temp gun they can be trimmed with the tiny allen screws on the bottom of the fuel dizzy. all that should help net a bit more power and throttle response.

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1985 300D om617: 8mm M pump 175cc 5200rpm, holset he221w @ 30psi, large A2W ic, compounds on the way.
KD9AFT
A&P