Changed temperature sensor in engine. Developed a miss especially under a load . changed wires , coils , ox sensor , plugs , changed leaking intake gasket ,cleaned throttle body and EGR valve. Little peppy but still can get rid of the miss ?
If your miss is more prevalent during high throttle application, your fuel filter may be clogged. This is a generally overlooked item of maintenance.
Also, you may benefit from a Seafoam treatment. Buy a can and put half in your gas tank with a full tank of gas. For the other half, with the engine running, pull a vacuum hose that goes directly to the vacuum side of the throttle body (ie, no lines with a check valve) and let the engine vacuum suck it directly into the motor.
The Seafoam in your tank will slowly clean your fuel injectors, and the Seafoam through the vacuum line with directly clean any carbon deposits that have developed in the combustion chamber. Be warned, there will be copious amounts of smoke while the engine burns the Seafoam. It is not harmful for the engine, but you probably want to limit your intake, as with any internal combustion exhaust.
Are you positive it’s a true miss? If so, it should store a code, most likely identifying the cylinder. Most auto parts stores will read the codes for you for free.
If it’s not a true miss but just rough running another common problem is a vacuum leak. Check all vacuum hoses for cracks or loose connections. Look online for different methods of finding leaks; one popular method is to use carb cleaner or starting fluid (flammable! Be careful and have an extinguisher handy!). Spray it around suspected spots; if there’s a leak, the engine will change speed as it sucks inthe flammable spray.
I have a 2000 SL2 with 1.9 liter L4 engine and 4 speed automatic transmission. It has 125K miles on it, and I’ve owned it for five years. It’s my daily driver.
I really don’t have anything to add to the OP. Except my transmission just went sour.
Yesterday, while driving home from work, the transmission was stuck in 1st gear. I tried everything to fix it while I was driving, but nothing worked. So I had to drive at 25 MPH @ 4000 RPM all the way home. 
I just removed the transmission’s valve body, and ordered another.
Is the check engine light on?
If no, it isn’t a miss.
If yes, have you read what codes are there? Have you checked the compression on the affected cylinders?
Fuel, air, spark, at the right place, at the right time, in the right amount. If there is a misfire one of those is out of whack.
If it’s idling at high RPM and running rough then the intake gasket may be leaking which is a common problem with this car. It’s a cheap but somewhat aggravating repair if you do it yourself. I think you have to remove the power steering pump to get to some of the bolts. You can test if it’s leaking by spraying engine cleaner around the intake ports to see if the RPM changes when it’s sucked in. I use to do this with engine starting fluid but had a plastic intake manifold explode when a sticking valve ignited it.
And an FYI to all SL-1 owners who use the power port to charge stuff. It’s on the same circuit as the engine management computer. Blow this fuse and your engine quits. You’ll know this because the instrument cluster lights will go out. Carry an extra 30 amp fuse (large size) in case this happens. This is located in the fuse box in the engine compartment and not the one in the passenger compartment. You can also sacrifice another fuse in an emergency. I think I used one for the air conditioner when I blew this fuse at 4am on the highway. So a flashlight helps if this happens at night.
PS, the manual I used didn’t list the correct number of bolts for the power steering pump. almost broke it off trying to remove it.
So your Saturn is missing? Perhaps you forgot where you parked it last?
What is “missing” in this context? Misfiring?
Yes.
Thanks.