Holiday rambler aluma lite 454 tbi too rich won't start

On this system map sensor: high vacuum is lean, low vacuum rich. On coolant temp sensor: high temp is lean, low temp means rich. This of course is how it is supposed to work. Sounds like you have checked all of this out already but what if the ECM is ignoring all these inputs? Any way to sub in another ECM to rule it good or bad? I would go there next.