I will pass this along for what it is worth, I have a '89 240, 250k that I used in my sales work. After a long drive of 2hrs or so I would come out after a sales call and it would not start. I would set for 20-30 min then it would start. I fought this for 6 mo trying all kinds of solutions. I did replace the crank sensor. The problem turned out to be the crank sensor gap was too large and when the engine warmed up the bell housing expanded enough that the gap increased and no signal. I ground the mounting tab for the sensor down a little to decrease the gap and my problem was solved. I found the problem using a timing light on coil wire and noticed the sporadic spark when it would not start...that lead me to the crank sensor. Good luck