What would cause the multiple misfire code in a 97 olds Bravada. I have changed air filter, plugs and wires, rotor and cap, solenoid. Also where are the sensors located that would give this code. The car runs smooth but the sensor says otherwise.

What solenoid did you need to replace?
Have you had the fuel injectors professionally cleaned? Not the stuff you put in the tank; the only thing that stuff cleans is wallets. The "good stuff" could harm the tank and other components, so it goes in at the engine and properly cleans the injector nozzles.
Sticky injectors can cause multiple and random misfire codes.

Multiple misfire codes can be caused by many things; e.g. improper cross-referenced spark plugs, worn spark plugs, deteriorated spark plug wires, bad coil pack, bad Crankshaft Position(CKP) Sensor, bad Camshaft Position (CMP) Sensor, failing MAF Sensor, dirty or sticking fuel injectors, clogged fuel filter, dirty air filter, bad gas, or failing ECU. Sometimes, even corrosion on the pins or connectors going to the ECU or sensor can be the culprit. MAF Sensors can sometimes be cleaned and the multiple codes will go away. Take a systematic approach and rule out as many possibilities as possible.