It is a 2003 ES Lancer 2.0L. Has 66k miles on it. All of a sudden after 10 years of problem free running the car is having weird start problems.

It started several months ago with crank times being instead of normal ~2 seconds or so to be 4-5 seconds, rarely.. maybe once a week. It went on like that for about a month. Then once a week or so it would not start up on the first try, if I held the key it would just keep cranking and cranking but not starting. Its completely random, it could be after having the car off for just a few minutes after a long drive or it could be in the morning, it doesnt seem to matter if its a cold or hot start.

I took it to AutoZone (since I thought perhaps my 1 year old battery is dying), they ran tests on the battery, its fine. I did this 2 times at 2 different AutoZones.

Took it to 2 different mechanics, since the problem is sparadic they cant pinpoint what it is, but both agreed its likely Crank Shaft sensor (2 pieces that make up that thing).

So I had the following done:
Ignition Wires replaced
Spark Plugs replaced
Alternator Serp Belt replaced
Cam Position Sensor replaced
Cam Positioning sensor replaced
Timing Belt replaced

All of those have never been changed before so for a lot of them it was time anyways.

Problem persists. For 3 days the car started just fine. This morning it started just fine, and then about 4-5 times after that while I went about my day.

But then all of a sudden it took about 10 tries to start it up, and this is after the car was off for about 10 minutes after driving for 90 miles. So not a cold start. Drove for another 5 miles, stopped, started just fine, tried stopping starting a few more times, starts just as its supposed to every time (2 second or so crank time)... wtf :/

What could it be? Is there perhaps a known issue with Lancers? Has anyone encountered this?

Basically to sum it up, the car can run perfectly without any issues for a week, then all of a sudden take several tries to start, then run perfectly for a week after that...

PS - one other thing I noticed that started around the time this started (i think)... if I put the car in Park it momentarily drops the RPM to about 300ish range for a few seconds, but then picks it back up and sits stable at 800ish as its supposed to. I am not sure if this is normal though, I cant seem to remember 100%.

overall while driving the car it seems to run just fine, never has any issues.

I am not a car guy... so I dont even know where to start, but hopefully I can get some guidance on here before I go spend money replacing parts that dont fix the problem (like I guess replacing Cam sensors etc (about $220) was a waste of money since it didnt fix the problem. Could it be fuel injection system?

Could I have "taught" the car how to inject fuel wrong? When I had the battery replaced about a year ago, the car would stall unless I accelerated for a while (I guess the computer had to re-learn how to inject the fuel or something)... could it be that when it was learning I taught it wrong and now it doesnt inject enough? Is that possible? Should I maybe try to "re-teach" it?

Thanks for any help guys!