troublecode 12 problem

[akamon]

Hope the following is not too convoluted: here goes. (this is for a 95 4 cyl dx camry). december 07 after experiencing numerous intermittant starting problems and taking it in to our toyota techs, it was decided to simply start replacing parts and see if problem would stop. replaced ignitor first and problem persisted about 3 weeks after, so replaced with new distributor (factory spec'd). This seems to have fixed original problem. Now for the weird part. During all this I took the trouble code and got 12 repeatedly, even after resetting. The techs said that that code was from the car failing to crank, and my research confirmed.
last week the check engine light comes on, I check for codes, and get 12 AGAIN! clear efi by disconnecting battery; still get check engine light and a 12 code. My research says: "no ne or g signal to ecm" and check camshaft position sensor and crankshaft position sensor. (car IS starting fine and no performance issuses). My research seems to say that only 6 cyl camrys have separate camshaft position sensor under timing belt cover, but it's not clear if this is definitive, so I call our toyota techs who say that a 95 4 cyl has it built into distributor.
Is this correct? Also, where is crankshaft post sens for my car?
Further, have read several instances on various forums of people going nuts over an intermitant starting/ stalling problem, getting a 12 error code, and after replacing everything including the ecm, it turned out to be the cam pos sensor.
sounds like my next step is to replace ecm, but before spending the big bucks for that, thought i'd run this up the flagpole and see if anyone has any other input.
I guess the bottom line is: want to check both post sensors first before replacing ecm, but can't tell if my vehicle even has them. Is there either a crankshaft position sensor, or a camshaft position sensor that i could check with a voltmeter on my vehicle and where are they (intergral to distributor or not)?
thanks in advance