When my 1991 Isuzu trooper reaches normal oper. Temp. It dies and I have to wait till it cools down and it will start right back up and go some more till it reaches temp. Again. Runs great cold but when at temp. Will die. Will crank and die crank and die until it cools down then will run like a charm. Any ideas?

Once it dies, run tests to see why it will not restart.
Do It Yourself Diagnosis and Repair

great question, (old)
oil and water do that.
or not changing oil until 25,000 miles like some dweeb, synthetic oil users suck in to the lie.
or driving only 1 mile per day (short trips)
the engine needs to reach full operating temp to burn off all that water.
gasoline burns into CO2 and water. so water happens
here.

or its a FORD (LOL)

Are the heater hoses getting hot ? Is the engine reaching normal operating temp ? Is the radiator full of coolant ?

Replace tempature sensor

1993 isuzu trooper idle controle air i nead the something

I might need a little more information to accurately diagnose situation but I always like to start with the thermostat.(touch top radiator hose if it is cool with temp reading high its probably thermostat) This device is supposed to open up when the engine reaches operating temp. to allow coolant to flow. If it is stuck it could easily cause the overheating condition you are experiencing. Some more info such as does it only overheat when sitting still or will it overheat when moving down the road. If only when sitting still I would suggest a problem with the cooling fan. If it is a gradual increase while driving based off the age of the vehicle I might suspect a clogged radiator. If this dont help try telling me more about it and I will be happy to provide more insight.

Check the sensor which controls the cooling fans that cools the radiator it prevents the engine from over heating and allows the temp gauge to stay at normal range.recently had problems with my 2003 impala overheating it was the sensor had the thermostat replace as well.

egr valve is not opening up when the engine reaches it normal operating temperture

It actually could be a number of things. I need to ask you more questions to narrow my prognosis down. You mentioned the weather being cold, lately. How cold? Freezing?When was your last tune up and do you eventually get the car started after trying for a while? If you do how does it run?

I have a 1991 isuzu trooper and if they're anything similar it's on the right side (driver side) of the engine down lower under the exaust manifold. sort of near the dipstick.