I've been having poor running issues with my '78 262C. Gas mileage has really gone down hill and after driving for about 30 minutes, the engine begins to buck and will eventually slow down to the point that there is barely any throttle response. If I take it out of gear and floor it, the RPMs top out at around 3000. It will eventually stall out. If I let it sit overnight, it starts right up, drives fine for a bit then starts bucking again. I replaced plugs, wires, coil, distributor cap and rotor, fuel filter (which was full of crud), air filter, oxygen sensor. Dropped the fuel tank and cleaned it out and replaced in-tank fuel sender and filter sock. Still had performance issue. Initially it starts up fine and idles great with great throttle response. I checked the cold start injector and it works fine (on when cold, off after warm up)and I checked the auxiliary air valve and it works fine too. Got frustrated and took to an independent Volvo garage. They checked the fuel pressure which was good and did a test of the Control Pressure Regulator, which checked bad. Would a bad CPR cause my symptoms?