Realizing that there is "more to the story"...

If: Ignition parts are all verifiably clean and in good condition

If: Throttle is clean

If: ECU's are all working equally after swapping between identical happy and not-happy cars...

If: Timing belt proves to be on the correct tooth (I have seen good ones jump one or 2 due to deteriorating timing covers dropping bits into the gears)

I would look at 2 things:

Inlet air hose from Air Mass Meter to throttle body- cracks do develop and sometimes only open up when engine moves around on its mounts (i.e. under acceleration)

Or Fuel pressure regulator. The entire mixture depends on this functioning correctly. Often they make the engine too rich or hard to start but other failure modes are possible. It's 20+ years old. Good replacement part to throw at it. As always, check the vacuum line for gasoline in the line- that would be proof of failure.

--Rob