buick starts and runs until it gets warm not hot shuts down wont start until cools down? then starts and runs again until warms up

well,something is wrong, or it wouldn't be doing that,PEOPLE CAN LOOK ALL THEY WANT! One of my sons had one of these cars a good while back ,and it started doing bout the same thing.so,i told him,be there in a flash! i had some spare ignition parts from another car just like his.so here i go.i was guessing at it?tried to start it,and all it would do was just crank over and no start.so,next, i don't know why i did this,BUT i took the coils off and the ICM that the coils sit on,had a spare ICM and changed it out.put the same coils back on it,FIRED right up? he drove it to work,about 25 miles,all good.so,i took his old module by a parts store to test it,tested good 1st time. i told the parts guy to keep repeating the test, several times to heat it up some.about the 5th or 6th test it FAILED! may not be your problem,but won't hurt to check it.good luck.also i cleaned his MAF sensor a few days later,just because.