module

This is a newish coil pack purchased from Kirban as "AC DELCO COIL PACK #7637" <1k miles on it Module is working great and comes with MSD wires. Took off my car to run XIM setup, all work great with no sputtering or popping at WOT. Selling for $200 shipped for all 3. Came off my 1986 GN

Having a problem with the coil pack dropping two cylinders on the same coil. The drivers side coil #3 & #6 keeps dropping out while driving. It will loose spark and then a mile or two it will come back on line. Under boost or high rpms the ignition starts breaking up. Checked all connections...