2.9 randomly drops spark

[Roman Hernandez]

I replaced the ignition module for my 1990 ranger and that resolved my issue of not starting when hot but now, the idle randomly drops, hot or cold. Ive replaced the distributor cap, plug wires, coil and i am at my wits end. I know that it cuts spark from the coil itself. It should be noted that all though the idle randomly drops the car never shuts all the way off. Ive tried checking all my ground to no avail

 

[RonD]

Welcome to TRS

If you have a 2.9l then you have a timing light

Hook it up to each spark plug wire and test if you are missing the pulse when idle drops, pulse will get slower but will still be there, steady rhythm, it will be obvious if spark stops even momentarily

This will confirm a spark issue, if pulsing stops and restarts randomly
Also when hooked to #1 spark plug wire check to see if spark advance changes just prior to idle dropping

You can unplug SPOUT Connector after engine is warmed up, SPOUT is the spark advance from computer wire, if idle stays steady with no drops then computer is causing it