New plugs, new fuel filter, all coil packs and injectors check good with the olms test. Starts good and idles good at first then stalls or idles very low rpm. On the highway it has great pick up but as I slow down it stalls. Its at it's best at 65 mph. Better gas mileage now but still has a miss too.

First thing I would look for is a disturbed vacuum line which will cause rough idle. When replacing coil packs, you have to remove covers, etc. so when vacuum lines get old and dry, even moving one slightly can cause cracking, so look for loose or cracked vacuum lines around where you were working on engine. It may just be loose hose. Good luck

How about a defective fuel pressure regulator, buy a fuel pressure test gauage from Autozone and test the fuel pressure under a load and at idle..

Check for any trouble codes in the engine computer, and have the fuel pressure tested. If it is throttle body injection. observe the spray pattern of the injector when it pulses. You should see a cone pattern of the fuel spraying down into the intake. If it drips, or appears anemic, the injector might be partially clogged. Try some injector cleaner in the gas tank.

A rich codes is hard to get. Something is restricting the airflow or you have something wrong with the fuel control. Check the air filter and if it is good. I would wonder if you have a leaking fuel injector. Do you know how to do a cylinder drop test? How well does it idle? Does it smell of raw fuel at idle? Is it hard to start after sitting?

Good Evening, you might want to check those injectors, I can not remember for certain but that setup was sequential and when one or two have a problem it would take out the rest. Ohm out the injectors and see what you have there.

Have you checked your fuel injectors ?

From the Fuel End: check the power at each individual fuel injector. If that checks out okay: Pull and check (and replace if needed) the fuel injectors. These could be clogged or malfunctioning.
From the Electronic End: disconnect and check the Electronic Ignition Coil Pack for continuity and consistent Spark. This should have been checked first as a rough idle could be caused by this.
Let me know if this helped, or if you have additional questions of informtion. Feel free to contact me on FixYa.com!

could bea few things. Excessive moisure, low fuel pressure, Faulty coil pack, spark plugs gap or wires. Have you changed any of those at all? Let me know

Stalling does not sound like an alternator problem. You have concentrated on ignition issues, have you looked at fuel related issues, including fuel filter and injectors? Much, much less likely, but air filter would also come to mind.

The throttle position sensor has a small amount of adjustment in it. The plastic case has a slight slot in it. On the opposite side of the TPS on the air horn you will see a throttle stop with a hard to move screw. You need to get some play on that screw to have slack to adjust the TPS. I think it was good for 100+rpm at base idle.
This may help you, but check you EGR for diaphram and carbon buildup.