I just changed timing belt and water pump and car worked great but next morning rough start but after the first initial startup worked good all day until next morning. I knew I needed to fix this and of course my head is thinking you messed up the timing, I didn't want to mess with the harmonic balancer again it snapped off two of my extension the first time, it took a third one later on when I finally got a code for crankshaft sensor position, before replacing that I watched a lot of YouTube but my father the mechanic who doesn't work on Honda convinced me to get a new fuel pump mine was only a year old, it worked for the day the next day car acted bad again, so I but another part fuel regulator it's late in mail and I second guess myself so I order control module car works next day it's bad, see the pattern, fuel regulator ends up being too long and can't go on cause it hits air intake manifold, which while waiting on parts change gaskets on lower and upper plenum and valve, case, and spark plug tube gaskets and of course cleaned the carbon out also the EGR, so next part gas cap and car works great again until next day so spark plugs car works the whole day but not the next day. Finally change the crankshaft sensor and my car stops hard starts and doesn't start at all!!! I order starter I have my doubts of course it's the 800th part I'm buying but I'm stumped so I look for ground cables I I'm replace battery cables and clean a few others and find a couple loose ground but to no avail, I just stare at my engine looks like it's leaking? I live on dirt roads and it's been raining a lot so bottom of car is always dirty but I haven't been driving I check the dip stick plenty of oil in fact to much oil?! I didn't add any, take spark plugs out as suspected oil, it's saturated so much it can't spark but my seals are new, it's probably the easiest and cheapest thing to replace, PCV valve which I checked it rattles but it's holding so much pressure as soon as I took a spark plug out released the pressure. I thought about replacing the valve a few times but didn't cause I was so sure it was functional but tomorrow I get the new PCV valve and a nearly rebuilt engine* also oil and filter changed and touched up on the paint. So change your $15 valve I own a 2000 Acura TL had a code scanner didn't help.

 

Take solace that you are not only one that has replaced parts that were probably good. Think of it this way, there are many many people that couldn't change a light bulb, even with instructions and a picture diagram. Congratulations on fixing your problem and not giving up!