A buddy of mine with a 2000 Rodeo 3.2l V6 (with the plastic cover over the engine removed) washed his engine last night with some engine bright and a hose with nozzle. Afterward he fired it up to idle for 20 minutes and turned it off as he noticed no issues. The following day (after a thunderstorm that night), he started his car and noticed pretty bad lugging when driving but no issues when idling or when in park and revved up to 4k RPM. Where do we go from here? My thought was that water might have gotten into the fuel so he tossed some Heet in there (I have yet to hear back about the progress with that). The only other thing I can think of is that water got in an electrical connection, but I don't know my way around these engines so I don't know where to start looking. Where should I check and if possible, can you take a pic of the area in question for my reference?

I really appreciate all the help I can get.
Thanks,
s