89 LX - Extremely rich & pinging under light throttle

Fuel pressure regulator getting any vacuum at all? No vacuum = open all the way. Also pinging is usually a sign of over advanced timing, crap gas, or a combination of the 2 if I'm not mistaken. Sorry can't help more couple things to check anyhow.

do a few things here... hook up a vacuum pump to the regulator and see if more or less vacuum has anything to do with how it is running...

also

make sure the timing is set properly

and

check for leaking fuel injectors by hooking up a fuel pressure gauge to the rail and looking for pressure bleed off.

leaking fuel injectors can cause poor running and excessive fuel use

+1 on the leaky injector, don't know why I didn't think of that just replaced one 2 weeks ago. Pulled the plugs and all looked good except one was fouled black and stunk like gas. Changed that injector out and am finally getting alot better gas mileage (mine wasn't leaking enough to effect performance but killed my gas mileage)

Ensure your vac lines are correct. It sounds like you could have a MAP sensor issue.

Be sure the EGR is connected to the EGR solenoid (that a line isn't misrouted).

Be sure the caris up to temp when pulling codes.

Good luck.

A block in the EGR system will cause a car to increase cylinder temp and detonate

Code 22 MAP (vacuum) or BARO signal out of range. The MAP or BARO sensor is pretty much the same sensor for both Mass Air & Speed Density cars. The main difference is where it is connected. Mass Air cars vent it to the atmosphere, while Speed Density cars connect it to the intake manifold vacuum. Its purpose is to help set a baseline for the air/fuel mixture by sensing changes in barometric pressure. The MAP or BAP sensor puts out a 5 volt square wave that changes frequency with variations in atmospheric pressure. The base is 154 HZ at 29.92" of mercury - dry sunny day at sea level, about 68-72 degrees. You need an oscilloscope or frequency meter to measure it. There is no way you can use a common cheap voltmeter or DVM to accurately measure the output signal.

The MAP/BARO sensor is mounted on the firewall behind the upper manifold.

Baro or MAP test using frequency meter - run the test key on engine off. The noise from the ignition system will likely upset the frequency meter. I used a 10 x oscilloscope probe connected from the frequency meter to the MAP/BAP to reduce the jitter in the meter's readout.

If it is defective, your air/fuel ratio will be off and the car’s performance & emissions will suffer

Some basic checks you can make to be sure that the sensor is getting power & ground:
Note that all resistance tests must be done with power off. Measuring resistance with a circuit powered on will give false readings and possibly damage the meter.
Check the resistance between the black/white wire on the MAP/BARO sensor and then the black/white wire on the EGR and the same wire on the TPS. It should be less than 1 ohm. Next check the resistance between the black/white wire and the negative battery cable. It should be less than 1.5 ohm.

The following power on check requires you to turn the ignition switch to the Run position.
Use a DVM to check for 5 volts on the orange/white wire. If it is missing, look for +5 volts at the orange/white wire on the TPS or EGR sensors. Use the black/white wire for the ground for the DVM.