i need help. got an 87 k5, with a rebuilt jasper 350 tbi with 20k miles. dies when in gear at idle, and when slowing at stops. heres what i have changed. cap, rotor, plugs, wires, map sensor, o2 sensor, swapped ecm's, ignition module. seems to be losing timing. if you disconnect the plug for the timing going to the ecm, it seems to run fine. i would appreciate any help. thanks.