Need MSD HEI help

[ndopita]

I bought a new MSD module with rev limiter for the HEI in my 69 c10. Installed it correctly and ground it to the negative battery terminal. Now the engine will barely run. It sounds like it is running on 1-2 cylinders and won't exceed ~100 rpm, then dies a few seconds later. I thought I had a defective module so I exchanged it for another one, same problem. I thought maybe my stock coil wasn't good, so I bought the overpriced MSD one recommended for the module. Same problem. Put the stock stuff back in, runs just fine. MSD tech was no real help so I figured I'd ask on here if anyone had any idea why I'm having this problem. Thanks for any input.