Surging at at all times, new Howell TBI installation

Been trying to solve this for over one year. Yes, one year. The vehicle has not moved one inch under its own power due to heavy surging. I am completely desperate at this point and will most likely sell this possessed vehicle. This will be a summary hang in there: Howell TBI installation. Fairly unmolested cj7, 1986. Upon starting, it always surges no matter what you do, warm, cold, accelerate. The engine cleanly revs up to about 1200 and goes down to 400 then catches itself and repeat. I have noticed the injectors stop firing at the peak and then start again. Okay, fuel pump has been changed with new unit-10psi. Dead head pressure at 75 psi. Volume is about 1 gallon a minute. ECM has been changed, throttle body has been changed. CTS, TPS, MAP, have all been changed. Distributor has been changed. Ignition module has been changed. Wiring has been checked over and over and direct power has been applied. Fuel relay has been bypassed. IAC appears to be going in and out with the surging. EGR and all vacuum ports have been plugged or removed to eliminate leaks. Manifold have been resurfaced and pressure tested. Plug wires, cap, rotor new.
That's about it I think. Had a GM master tech look at it. Baffled.