After starting and when engine is a little warmed up, is it difficult to raise the engine speed?

Thinking about what may get bumped around when doing the water pump job, maybe it's the vacuum line to the ICM.

That line looks more like a fat dirty-white wire than a tube. Look at the ICM, you will see a vacuum actuator, similar to the ones that operate the air vent directions. The line is visible there.

It runs with the under-engine-front wires and comes up aft of the distributor. It then goes up to a 90-degree rubber connector which connects to a brass fitting on the intake manifold.

If the ICM gets no vacuum, the spark advance is impaired to the point of the engine having no power. Q.E.D.

Good Luck,

Bob

:>)