after cleaning my incredibly dirty throttle body (in which all of the vac openings were clogged) i noticed my intake manifold was as dirty or dirtier inside. at some point in the cars fairly recent past (i just bought it), there was obviously an oil leak. it could have been because the flame trap i replaced was also almost completely clogged, or somewhere a gasket blew and no one bothered to degrease after the oil shower. either way its very dirty down there. i changed the oil and have been watching the level pretty closely. if there is a leak, its so slow its not noticable - atleast not by using the dipstick. but it seems to me the only way to make sure is to clean the engine and look for oil after every drive. so, i want to clean my system internally and externally. i planned on taking off throttle body, intake manifold, exhaust manifold, and head cover in order to thoroughly clean and replace gaskets. i'd use this opportunity to clean the outside of the head and block thoroughly by hand because of the easy access to places that were hidden by the manifolds and stuff. is this a good idea? what gaskets besides the obviously would i potentially need to replace? i was going to change the timing belt as well, but dont know how to replace the 3 seals that are recommended to change. im assuming this would be a good time to do that though. now, i've also seen pictures of disgusting gunk coated valves so gross i've been having nightmares. is there any way to clean them without taking the head off/engine out? can i hook up some sort of cleaner to the intake and use the starter to pull the cleaner through the head? is there anything else i should do while i have all this junk off? i need to plan this out pretty well so i can order all the gaskets and parts i'll need before i start. this is my only car and can't be out of commission for too long or im stuck at home! thanks alot

handsome greg