I have a 98 jimmy that has had an intermitent stall problem for over 2 years. I had changed the fuel injectors, spider, distributor, plugs, throttle position sensor, fuel filter, air filter, fuel pump, etc....nothing seemed to help. I noticed that the stalling would come in waves of frequent amounts followed by long periods of non-stalling. I discovered that the 4 prong connector that plugs into the ignition module on the coil was defective. What happened was the little wires were not making good contact with the module. This is an easy repair because the connector is visible and accessable from the top of the motor. Look for the connector that has 4 wires coming out of it. With the motor running wiggle the wires. If you have an unexplained intermitten stall with no check engine light then this is your problem. Disconnect the plug and inspect for dirt. Clean the plug and put some spark plug grease on there. Also, take a screw driver and slightly bend the 4 little prongs that protrude from the module side. Be carefull not to break them, if you do it's going to cost $79 to replace the module. Now reconnect the plug. Take some electrical tape and secure the plug to the edge of the female side of the plug.