Oldsmobile/Buick Repair: 1990 BUICK LESABRE CUTTING OUT, coolant temperature sensor, throttle position sensor

Question
Hey Van,
      Back in May05 my 90 lesabre custom started to hard start as if fuel was not getting to the engine, and it would also hard start when the engine got hot,but when the engine cooled down it would start.Also it would cut out during driving or at a traffic light.I had a new fuel pump put in,new fuel filter,new airmass flow sensor,new air filter,new coil pack,new ignition module,I replaced a vacuum hose that looked worn out.Also changed the oil & oil filter,put in some fuel injector cleaner[marine auto).Also when the engine got hot looked as though there was a slight antifreeze drip.After making all of these repairs the car ran perfect from may to the end of september.Once again it started doing the same thing.I discovered that the cooling fan was functional but was not coming on. I had the fan bypassed so it runs all the time the car is running also i havent seen any antifreeze drip.After bypassing the fan the car hasnt cut out while driving as yet but it has cut at a traffic light.As the car idled the engine would start to jump then the car dash lights would come on and the car would cut out but start back up right away.I have not made any repairs to the egr valve system or the throttle position sensor or the AIC,also i have never changed the oxygen sensor.Could one of these be the problem or is there somethingelse that i am missing.This car runs perfect!!!!!!!!This is the only problem that i am having.(PS.. Its been about a year and a half since i had a tuneup)I dont know if that might help.I would greatly appreciate any help with this problem, thank you in advance for your help.  

Answer
Hello Orrin,
I would check the engine coolant temperature sensor. Here is a link, and some specs for testing it.

http://www.chevytalk.org/threads/showthreaded.php?Cat=0&Number=1366279


This link is also something to consider, even though you don't drive a Ford, this is relevent.
http://www.fordscorpio.co.uk/cleanmaf.htm

Van