Welcome to FTE.

If it's missing, you should have a blinking CEL when it does this & misfire codes should be set in the computer for the cylinder/s that have the problem, so any trouble codes can provide good clues & shorten your trouble shoot.

A miss under load is usually a sign of a weak spark problem. Like a loose plug wire, bad plug wire internally, cracked or chipped internal or external plug ceramics, excessive plug spark gap, a bad coil pack, or low B+ voltage to the coilpack, from bad wiring, connector, bad battery, or alternator.
The coil packs of that era were known to crack underneath, out of sight & cause mischief.

SO, seeing as how this is a 94 & it's OBD-1, the DLC is under hood, so the results the AZ guy had are suspect, if he wasn't under hood with his code reader!!!!

You can pull the codes yourself, using a jumper wire, 12 volt test lamp, analog multimeter, or watching the in dash CEL blink or the meter wave the codes.
Where to place the jumper wire & how to hook up the meter or test lamp & read the codes, is outlined in a thread link in the "Tech Info" thread atop this forums thread listing page.

So, maybe begin with scanning for codes yourself, if the AZ guys results are suspect.

OR, raising the hood at night & look for plug, wire & coilpack arcs & sparks & maybe consider doing a "wet down" test of each plug, wire & the coilpack, with a spray bottle of water & look for arcs & sparks, or a rougher running engine.

Did the miss come about After the plugs & wires were replaced???? If so, concentrate your trouble shoot there. I once had an intermittent under load miss, that was worse in wet/damp, or rainy weather, on my then new 99 Ranger, that was traced to a cracked #6 plug ceramic, when the Dealer did the wet down test.

Just because the plugs & wires are new, doesn't automatically earn em a pass, make them earn that good label. If the wet down test proves naught, pull each plug wire & make sure it's end to end internal resistance is within spec using your multimeter & the readings don't change when you flex the connectors on each end. The resistance should be about 1000 ohms/inch of length, 30,000 ohms max, no matter the lenght. Make sure the wires are snapped on good & tight on both ends, and are routed to the correct plug & coilpack terminal, using the factory routing & All of the wire looms.

If that doesn't do it, pull each plug & closely inspect each plugs internal & external ceramics for chips & cracks. In my case, the Dealers lead Tech had cracked the #6 plug when he installed it after a head change.

If that doesn't do it, maybe consider pulling the coilpack for a bench test. Most autoparts stores can do it & at no charge. Maybe take your spray bottle along, to wet it down on the bench test, if need be.

Other things can also cause an under load miss, like a lean mixture from a vacuum leak, low fuel pressure, acting out EGR system, ect, ect, so the trouble shoot scenario can be lengthly in stubborn cases, so don't get discouraged if you don't get joy right away. Be thorough in your trouble shoot & put everything on your suspct list to begin with!!!!

A bunch more thoughts for pondering, let us know how it goes.