Your 1993 should have an OBD-I computer system.

Have you checked whether you have a code set for the EGR system by doing the key
On, Off, On, Of, On
Sequence and counting the flashes of the Check Engine light?

The EGR systems of 1992-1995 systems are complex.

The EPA required Chrysler pcm software to turn them on to fully flow maximum egr gas flow if anything went wrong. This "Full On when Failed" condition causes engines to easily stall out, prompting owners to get them fixed.

The EGR does not turn on until exhaust backpressure is more than 3 psi, which on the factory exhaust system is around 60% load.
There is both an EGR valve and a separate "EGR Modulating Valve".

The JTEC computer periodically tests whether the EGR system is working by waiting for backpressure above 3 psi and a fairly steady throttle. The computer then turns the EGR on and checks the O2 sensor to see if the air to fuel mixture slightly richens to less than 14.7
Then the computer turns the EGR flow off and sees if the air to fuel ratio slightly leans to more than 14.7

As rough rules of thumb:

NOx pollution reduces if the cylinders are cleaned out of carbon deposits so that the "Real World" compression ratio decreases.

NOx pollution reduces the higher percent ethanol in the gasoline mix.

NOx pollution reduces as cylinders get richer air fuel ratios.
One or more lean cylinders caused by partially plugged fuel injectors can cause a failed emissions test.

1992-1995 factory Dodge catalytic converters were so called "2 Way" devices that reduced HC and CO but not NOx.

1996+ catalytic converters were 3 Way devices that reduced NOx as well,
and so 1996+ OBD-II systems did not have EGR valves,
although their camshafts allowed more "internal EGR" during the overlap period.

Both 1992-1995 and 1996-2001 cat cons were very prone to break up inside and partially plug up, greatly increasing exhaust backpressure. There was a recall on this around 1998.
This high backpressure on 1992-1995 systems blew out the bellows on the EGR Modulating valve too.