I have a 1980 TR8 with 175CD Zenith Stromberg carbs. Car has lots of power but the engine decelerates very slowly from 2500 RPM to idle. They have new diaphragms, good idle speed at 750 RPM. Mixture seems to be good and both carbs are nicely synchronized. The throttle linkage is free and the they both return to the idle stop when released. These carbs do not have the bypass valve so this is not the problem. The timing retard unit is good also. Has anybody run into this problem before? I have no interest in installing a 4 barrel and will keep these carbs, first problem I have had with ZS carbs in many years of use on both TR6 and TR8's. Appreciate any ideas you may have.