I have a 1991 jeep wrangler YJ with the jeep 2.5L motor. I just rebuilt it and now when you start it it runs rough idles very rough at first then dies. When driving as you first take off from a stop it isis very rough until your rpm gets above 2000 it is very rough once it tachs above 2000 it runs great. I have had checked and rechecked and taken it a mechanic who has also checked and rechecked everything. So far it has new plugs wires, distributor

Well, without checking it myself, I can only throw a guess out there at you. It sounds to me like there is a vacuum leak there somewhere. Usually the symptoms you describe are caused by vac leaks. It could be a hose, it could be intake... check everything.

Replaced all the van lines and have already checked for leaks by hand and by gauge there isn't one. Intake, timing, injectors are all good, I have 142.6 lbs pressure exactly in all 4 cyl. I've replaced all the sensors. All hoses and lines have been replaced

I would replace the Ignition Control Module (ICM). Super easy and cheap on that vehicle. Only use the called for Champion spark plugs (no substitutes).