Welcome to the forum
Good to post the code with definition just in case you had the wrong definition, lol
P1121 Throttle Position Sensor Inconsistent with Mass Air Flow Sensor
The computer knows what engine it is running, 2.3 liter in this case, so it knows exactly how much air should be coming in at any RPM and throttle position, its just math
What it doesn't know is the WEIGHT of that air, which changes ALOT, from sea level to 5,000ft elevation or from -30degF to 120degF air temp
That's what the MAF sensor is for it "weighs" the air coming in
So the Code is telling driver that the range of MAF sensor, at a specific RPM, doesn't match up with Throttle plate's position
This code could be caused by the stalling out, or the reason for the stalling out
And doing it ONLY when on a bumpy road will be hard to figure out
I assume you have unplugged each of these sensors and checked the wires, and connectors are tight
I would suspect fuel issue first because you have a dual spark system, so electrically spark cutting out on one set of spark plugs shouldn't matter
You could warm up the engine then shut it off, then unplug the 3 wire connector on one of the coil packs
Restart engine and make sure it runs smooth, no misfires
Shut off engine and plug coil pack back in and unplug the other one, same test
If engine doesn't run well on one of the coil packs then you can swap them around and retest, if problem stays with the coil pack replace it
This 2.3l Lima engine ran just fine on 4 spark plugs from 1974 to 1988, the dual plugs give it a bit more power, like the Dodge Hemi dual plug engines
And the Codes you are NOT getting are helpful
There are no fuel pump power codes, so fuel pump relay is OK, but the fuel pump itself or its wiring on the top of the tank may not be OK
And there is the Inertia switch in the cab, it should just popup and cut power to pump until you reset it, but............
As far as you know has the vehicle ever been in an accident?
If so and it was repaired, then inertia switch may not have been replaced and is cutting power to pump on bumps
EEC/PCM Relay, its in the engine fuse box
Swap it with one of the windshield wiper relays, should be same relay part number
Its possible but not likely the PCM relay is opening on a bump, but...............you should get a CEL on/off as computer reboots