my 94 gmc sierra 1500 will start then dies and then wont start again for awhile

yes, the intake air temperature sensor is sending bogus data or disconnected~ https://www.google.com/#q=1994+GMC+Sierra+1500++IAT+sensor&tbm=s hop&spd=9043524995793856051

this little goodie replaces the heat riser, stove kit, diverter, heat riser and thermal choke with two position throttle....all that in one goodie~

http://www.autopartswarehouse.com/sku/Standard/IAT_Sensor/SIAX32.html ~38.50 .... could be worse~

Intake air temp is not going to cause the engine to flood out, especially on an obd 1. Check your fuel pressure, could be the filter is clogged lowering the amount of available fuel and pressure, could be the pump is weakening with the increase in temperature from running both would not provide enough fuel preventing it from getting burnt properly causing the raw fuel smell. Could be a broken fuel pressure regulator diaphragm, causing the engine to actually flood out when it warms up and tries to idle down. Also check for spark after it dies, could be the coil or the pickup getting warm and quitting until it cools.

would an oxygen sensor in a 1990 sierra 1500 let the engine start and then die..i have to turn the key off then restart then it runs for 5 seconds then dies..if i keep doing this.. eventually it stays running..20 stars and stalls later..

Probably not, since it reverts to open loop when it's faulty and the data isn't read from it until the engine is up to temp. Open loop is a default presetting in the ecm that is run on a cold engine. You have either a fuel or spark issue.