Code reads number 3 cylinder misfire on my 98 saturn sl2. Changed the plugs and wires. Whats my next move?

Have you checked your spark plugs yet? This is a Cylinder 1 misfire. Most likely just plugs and wires but these also had an issue with the intake gasket leaking air and causing a misfire code. Spray carb cleaner or brake cleaner along the intake manifold where it touches the cylinder head and see if the engine almost dies while running, if so then you know yo have a leaking intake gasket.

You have a misfire on number 3 cylinder.What it means is that that cylinder is not contributing, this can be from a leaking intake manifold,and injector that is not delivering fuel correctly a coil pack to even a sparkplug wire that has worned out.To a sparkplug, If you want to do a tune up here is what you will need.

remove and clean the injectors
misfires are more injector problems than wires and plugs

If your getting a P0302 ( cylinder #2 misfire detected), the first thing to check is the spark plug. If it's new then the next thing to check is the plug wire. If it has individual coils, then swap it out with another one and see if the misfire moves too. If so then the coil is faulty.

Check fuel injector and compression in cyl. #5.

P0300 Multiple Cylinder Misfire Detected

P0306 Cylinder 6 Misfire Detected

P0451 EVAP Pressure Sensor Range/Performance

I have no idea what those last two are. Typo, maybe?

Your first two codes could be caused by old spark plugs and/or leaking plug wires.

Your EVAP code could be a bad fuel tank pressure sensor or a malfunctioning EVAP system. With that code, if you remove your fuel cap and get a whoosing sound, then it is an issue with your EVAP system not properly venting the tank. If you don't get that sound, then the tank pressure sensor is bad.

PO302 is being a misfire, could mean the plug is bad or the coil is bad for that cylinder. Which can give you the misfire reading and the system to lean codes. Check the #2 coil for firing.

p303 is a cylinder 3 missfire I woul first check the coil and then the ingnition module, Then if this dont work you could have a bad injector. If after testing and still no fix you should check the compression in that cyl.

cylinder 1 misfire and low compression. Plugs and wires changed plus new fuel injectors. The engines still misses and no one can find the cause. When put on the computer it read misfire cylinder 1.

Try a radiator flush with new coolant. Radiators tend to get clogged with **** and it can lead to the problems your talking about. What color are the tips of you plugs when you take them out. Have you had the codes read on the ECU?