Engine 85 49,000 miles just dies

49,000 miles and I am original owner. Bone stock, nothing has been changed. I have been through carb a coupe times over the years.
5 spd car and throw it in reverse and just dies when trying to let clutch out. No chugging, tach drops immediately to zero. I jumped clutch pedal safety switch and still same result. I wiggled tach wires under hood and can not make it die. It dies so fast it seems electrical. Carb does need cleaned again and I have been blaming the carb for it running a little rough but I am starting to think the dying in reverse is making its way to other gears. I down shifted to first at an intersection and it started bucking. Notice the tach was jumping zero to 2,500 repeatedly while it was bucking.
Any suggestions where I should look?

85 GT with 302. Just went through carb found bad large vacuum hose to egr plate in the front. All back together and ran better than it has in decades but still not fixed. (I only do about 500 miles a year.) It usually does this backing out of the garage and most noticeable in reverse. I thought it was fixed after first test drive. Backed right out of garage and ran sooooo smooth. Vacuum hose been a problem for several years I suspect. Second test drive with my brother and doing it again. The tach drops to zero just like it was shut off then immediately back up. On and off multiple times. Everything else is still running, ac radio blower motor. Im leaning towards Duraspark. Wiggled all the connectors at Duraspark and coil and could not replicate the symptoms.