I recently did an overhaul on the car (upper and lower intake seals, iridium spark plugs, IMT seals, brake booster fitting replacement, coolant hoses and water pump), and decided to give it a good engine bath. The car ran fantastic for about 10 miles, and then went into "limp performance". The engine is misfiring on cylinders 1, 3, 5. It's almost been full day since the wash, the car has been stored and drying in a garage with an open hood (about 40 degrees F) - no improvement.

From reading the forums, washing the engine compartment is a no-no, and most likely the misfire is a result of water entry into the spark plug bosses, or an issue with the harness.

What are my options? How little water is enough to upset the coils / plugs and is it really possible that 1,3,5 are all affected and not 2,5,6?

 

I think you have it correct but it won't dry out at 40F!!

I would take the coil covers off if possible. One side of the V-6 is hard to get to because of the intake. Then start and idle the car until it's good and hot. May need to do this several times to drive all the water out.
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