In the pursuit of FE you're constantly running low RPM engine on and off all the time which would tend to plug things up. My Mom had an old 280z that never got run hard (over 3000 rpm) and when I would borrow it there was no pep until I ran it hard for a while which would seem to clean it out and it would start performing alot better. Does anyone worry about that and if so what do you do?
Call me crazy (as usual), but I think an engine needs a good run-up at least once a month. Sometimes I find that I need to redline to squeeze onto the highway, or make that yellow light. Not only will it blow out the intake crud, but also any build-up in the CAT or general exhaust system. It probably gets small oil injectors going too. It can't hurt it -- every car was designed to run to the redline, if it's properly maintained, for tens-of-thousands of miles.
I still have some seafoam left, afterwards I'll switch to AutoRx.
A word of caution about cleaning the engine bay -- it's all for looks and can only hurt performance (with water and detergent getting in important parts, like the alternator). Back in the day when RH77 was a teenager and wanted to go cruisin', he would get the family minivan shined up and sprayed off the engine bay once. Turns out, water in the alternator creates a barely-running situation that freaked-out the recently licensed driver. After driving around at mostly full-throttle, things got back to normal, and RH77's parents consequently didn't ground him from the exclusive privilege of the '88 Plymouth. But despite the shining and polishing, nor the 3.0L Mitsubishi V-6 got the attention of the lizzadies :-(