Volvo Repair: Random delay while accelerating, fuel pressure regulator, hesitation problem

Question
I have a 1990 Volvo 740GLE 16 Valve auto wagon. I have a problem when accelerating either from a stop or a slow roll. When I give it the gas it feels as if the catalytic converter is clogged. Or the way a carbuerator car reacts when it has a bad accelerator pump. It bogs down, but if I let off the gas and accelerate very slowly it will eventually go. Or if I floor it, it will also slowly get up to speed(I don't like to floor it because it sometime pops and backfires). This hesitation problem doen't happen all the time. Sometimes it will do it in the morning when I first start it and sometimes it works fine. After I get off the freeway on my way home from work and I start stop and go driving it might start doing it too. It's random but annoying because I don't dare take off into any kind of traffic in fear it will take me forever to get going. Also when I first start the car I always have to hold my foot on the gas because the idle is very rough and it will stall.  After I've held it for a few minutes at about 2000 rpm I let off the gas slowly and it will idle but still rough. I live in Arizona and when I use the AC it really acts up. I have to shut off the AC to take off from a stop or slow roll. I hope you can help. If you need anymore info you can email me.  

Answer
If basic tune up parts are ok, I would recommend having a shop perform a fuel pressure check to verify good fuel pump operation and that the fuel pressure regulator is good. Then check the tailpipe emissions to make sure the fuel injection is functioning properly.

First thing that comes to mind is possibly a faulty air mass meter, but don't replace unless everything checks out good.