92 Asto AWD vin "W" bad milage

I got a 92 Astro for free. People that had it did not want it anymore, since they were moving.
At first the engine (vin W) seemed to run a little rough and I thought that it could use a tune up. I replaced plugs, wires, cap and rotor. Found out that the O2 sensor was bad and replaced it. Took out the EGR valve and cleaned it. Engine then would die at idle but ran down the road good. I replaced the idle air control valve and now runs runs fine during idle.
Shortly after getting the van for the first time, we checked the fuel pressure after start up and then turned off the engine. For about 10-15 minutes the pressure stayed above 50, at around 54.
I have put about 400-500 miles on it since then, and I am finding that it seems to be running rich, and the fuel economy for city driving is 10 mpg. When the van starts cold it usualy fires right up but emits a "puff" of smoke from the exhaust. When starting warm, I have to push the throttle to the floor to get it to start.
I have been looking all over for what might be the problem.
I have not yet replaced a MAP yet.
Could I be looking at replacing the fuel pressure regulator still?

And Lastly, has anyone taken off the intake manifold while leaving the AC lines intact that run to the compressor? How is it done?
Thanks a bunch.

And the van has 150,000 miles on it.

You have a bad fuel injection spider and or a bad fuel pump.

Thanks CD Smalley,

I have been looking more into it and and I am finding that the oil smells a little more like gas. I am going to look into replacing the CPI and nut kit. I have found some good info with pictures on this site about replacing them. I do need to save some money and get a CPI and nut kit.

Does anyone know a good place to get these kits and how much money am I looking at spending for them?

In the meantime I'll be changing my oil more frequently.

Best place I have found is fleabay. That was th ebest place I found for the spider. It was an AC-Delco kit and was much cheaper, even with shipping than the local parts store...

I had a similar problem with my 92 Astro vin W. There are 2 polyprpaline fuel lines that run from the outsice of the manifold to the spider injector. The GM term for them is the "Fuel nut kit". The pressure line developes a crack with age and mileage and begins to leak under pressure. By the way, the top of the intake comes off without removing the A/C. It is about a 20 minute removal if you have done it before. Take the top off and turn the key on without cranking the engine. You will most likely find your leak! Best place to buy the injector( if youve gotten this far, change it!) is Ebay. Ive seen the injector, fuel nut, and plenum gasket offered as a package.