1990 sierra hard to start,then idles high eng. light comes on veh.idles start to die then dies

When the engine dies the Check eng light is supposed to come on. You need to do a fault code test on the OBD2 engine control module.

You may have an idle air control motor issue ( IAC).This motor controls the idle on start up as well as normal driving conditions. Is the check engine light on. If it is it may give a hint as to what the problem is.The traction control light has no control as far as the idle is concerned,. It is controlled by the ABS system. Usually the ABS light will come on if there is a traction control issue.

first run high test fuel..then u might want to change spark plug wires..if u dont have check eng light on

could be a weak fuel pump or regulator fault (fuel) faulty relay pump/injection ether one. idle valve sticking. these will all need to be checked.

You need to test the fuel pressure with an accurate gauge. This engine is very pressure sensitive. It has trouble even running if the pressure drops below 55PSI.

Have you had your fuel pressure tested? Low pressure and/or volume could cause the truck to idle normally, but not be able to take any load. There is a very high failure rate on these fuel pumps.

IAC either dirty or bad

Sounds like the fuel supply through is inadequate. That is a Want-to-be fuel injection system that uses a relay to enrichen the gas mixture.

Solution could be a container of fuel system cleaner, and a spray or two of carb cleaner in the injector.

Other causes could be:
Failure of the "choke" to richen the gas mixture
Vacuum line leakage.
Fuel filter becoming clogged

Check to see if the pink wire on the mass air flow connector has voltage with key on.It come's from fuse #15 inthe under hood power box.Also called eng 1 fuse.If voltage is present try the old trick of using carb cleaner to see if you have a vacuum leak.that will also cause a high idle oon fuel injected veh.If you can't find anything ther your going to need to see your mechanic to trace the trouble tree down for that code.There is a long process for that code. Good luck.

Did you change the fuel presure regulator located in the throttle body?