rough idle on hot start

I have an intermittent problem with a rough idle on a hot start (93 explorer). On short runs - it may or may not act up, but after highway driving it always idles roughs and dies when turning engine back on. The fuel pressure is fine, O2 sensors new, just replaced IAC valve and was rewarded with 2 days of great driving: fuel consumption dropped, acceleration improved and shifting seemed smoother. Problem has returned: am thinking mass air flow sensor or EGR, PCV, maybe fuel pump?? Thoughts? I am on a tight budget and need to do home repairs.

Check the vacuum line to the fuel pressure for the presence of gas. Did you check how long it would hold fuel pressure after you turned it off? Should hold for 30 minutes or more.

The fuel pressure was fine 45 min later, so I am sure that is not it.