1995 Ford Windstar cranks, won't start

Car always starts when cold. When drive and car reaches operating temp, I park and come back 10 or15 min, s later, it will crank but not start, I put ignitionwire in spark tester-2 metal prongs about 1/4"apart with ground'g clip.I put a piece of paper between points and there was no mark or hole.I.E. There was no spark. This problem was intermittant-now it allways happens, IT ALWAYS STARTS WHEN IT'S COLD!-Needle must go all the way to the blue cold dot on temp guage. Engine lite does not appear when car running-only when turn key to on-which I think it always did. Everybody says computer(Big$) but what about ignition module, or crank sensor.I'm giving donation=maybe more. Ralphny104@nyc. Rr. Com