On a 1988 Plymouth Reliant I have no brake lights, fuse, bulb, and switch are all good, Anyone know where to check next?

Have you cycled key to retrieve trouble codes? Do you know how?

Have you cycled the key for retrieving any engine trouble codes? Is "check engine" light on?

Since the turns work in the back, that means the brake bulbs are good. Brake lights and turn signal lights share the same filament in the bulb.
There is a fuse for the brake lights. Then, there is a brake light switch on the brake pedal. You need a voltmeter or test light, after checking that fuse is good. Need to check if fuse has power on it. This is one of those fuses that are hot at all times-as long as battery is connected, voltage should be going through the fuse and up to the brake light switch. Check for power both places. The switch on the pedal is a simple on-off switch. When brake is depressed, the spring loaded switch is turned on-passing power on towards the brake lights.
But then the brake wire goes into the turn signal switch before going on to the brake bulbs...however, since your turns work good, I doubt if there is a problem in the turn switch. First check if the brake light switch is sending power on when switch is on.
Let me know what you find. Good luck.

check the continuity to the brake light switch near the brake pedal

The fuse box is located on the bottom edge of the dash no the drivers side, there should be a small panel you pull out. Based on the age of the car, it is quite possible that you have a bad fuel pump. Try giving the tank a good rap with a rubber mallet or wooden broom stick and see if it starts. Sometimes the jolt frees up the pump.

Check the bulb if it is good replace the turn signal flasher under dash (very inexpensive)

Hello compwizard
The next thing to check is the brake light switch. The switch is located
under the dash on the left side of the brake peddle bracket. There
should be constant 12v into the switch and 12v out when brake is
applied. Use a 12v test light or volt meter to check the switch. The switch is a fairly common cause of the problem you have.
Hope this helps

Sounds like a new headlight switch is in order.

I think about 10-15 mi less than 30 mph-library sec 629 has more info

CHECK ALL THE GROUND LEADS TO THE LIGHTS AND CHECK FOR CORROSION