[TR] Annoying "bulb-blub-blub" sound

[Joe DeMuth]

Does anybody know what causes the "bulb-blub-blub burble sound you get when
you let up on the gas, especially loud in higher gears. It sounds like muffled
explosions in the mufflers. My car (TR6) has started doing it excessively and
I really would like to get rid of it. So far I have adjusted the valves,
checked timing, checked the lean/rich mixture and all seemed fine. The next
step is to slap another set of Strombergs on to see if it goes away. I am
stumped. The sound started about 1/3 of the way back to Minnesota from the Hot
Springs British Car Week gathering in early June and has been getting worse
ever since. Other symptoms, hesitation on acceleration and some missing. The
distributor has recently been rebuilt by Jeff at Advanced Distributor so I
dont think that is the culprit.