I have little experience with cars i do know a little about them but i havent really worked on them. My 240 for the last few months has always started up and ran really good but sometimes it would just turn off and slowly come to a stop then after a few seconds it would start right up. Overtime it has become worse now it will not even start. I have been told that it might be a ICM (ignition Control Module) . does any one have any other ideas or thoughts about this problem?

 

first step, read the diagnostic codes. see this 7xx/9xx FAQ on that (the later 240's are virtually identical mechanically and electrically to the same generation 740/940 cars, only significant differences are 1) fuses and relays are in different places, and 2) there is no 'radio suppression relay' on the 240.
Engine and OBD Diagnostic Codes

assuming the car is turning over when you crank it, there's two fundamental reasons for not starting... 1) fuel and 2) ignition. a quick and dirty test, try starting it with a good 10-15 second crank (not any longer than this or you can overheat the starter motor), and immediately sniff around the tailpipe. do you smell gas fumes? if you do, then its more likely ignition. a better test is to do that same crank thing, and pull a spark plug. if its wet, you got fuel so probably no spark.

if you have no fuel, then things to look at are 1) are the fuel pumps running? (there are two, one in the tank, and the main pump under the car in front of the tank). the pumps should run about a second when you first turn the key to II ('run') then they stop, until the engine turns over. 2) the crank position sensor, formerly considered a rock solid part, has been increasingly showing up as flakey after 20+ years.. this or its wiring. without this sensor, the ECUs can't tell the engine is turning over, and won't run the fuel pumps or injectors or spark. its tucked in back of the engine near the top of the transmission bell housing.