1990 5.7L issues

[90G30]

Hi,
I recently purchased a 1990 Chevrolet G30 1-ton cargo van. I am the second owner. It was purchased new by the City of Phoenix and has just over 88,000 miles on it. I flew down to Phoenix and drove the van back home to Las Vegas. It ran really strong all the way home (5 hr trip) as long as I was at highway speeds. I noticed after a stop, that it sputtered and bogged while getting back up to speed. Once at higher RPM's all was fine again. I should mention that this van has the TH400 automatic transmission. I was very happy with how it performed through the mountain grades and passes and had no problem keeping up with traffic at 65-75mph. When I first started it up in Phoenix, I noticed a loping idle and hesitation at lower speeds but, once warmed up, that seemed to go away. So after having it home for a few days and driving it around the neighborhood, (I haven't had time to go to the DMV yet with my work schedule) I began to get more familiar with it. When started cold, it would idle up and down, almost stalling but then catching itself and revving up again. Once warmed up the idle smoothed out; however, whether warm or cold, the hesitation and bogging was still there. This would occur when starting out from a stop pretty much until it got up to maybe 30mph. I had a few days off over the holidays and decided I needed to try to do something about this. I paid $1600 for the van and I love it! To me, it's worth putting a little money into to get it running properly. It has zero rust and doesn't leak a drop of fluids. So, I began by cleaning the throttle body as best I could and that helped the idle some. But while I was doing that, I noticed that both injectors were "dripping". They both made a cone-shaped spray, but they also had a nearly solid stream of fuel running down the center of the cone onto the throttle plates. I'm no top mechanic by any means and I've never owned a TBI vehicle, so this is all new to me. But I'm pretty sure the injectors shouldn't drip like that. So I replaced both injectors, along with new O-rings, which I lubed with motor oil, replaced the fuel pressure regulator diaphram and the fuel meter cover and fuel meter outlet gaskets. I turned the key a few times to build fuel pressure, crossed my fingers and started her up. She was hard to start and I had to keep her going with the gas pedal. But the spray patterns look good. Fine, cone-shaped misting with no dripping. But I couldn't get her to idle! I looked all around for vacuum leaks and found an old, crumbling hose running from the intake manifold to that round vacuum pot and replaced that with a new line, but nothing changed. Then I unplugged the coolant temp sensor and she idles on her own with it unplugged, but lopes up and down. My next step is to clean the IAC valve and replace the coolant temp sensor and fuel filter. Am I correct in assuming that the reason she ran well at high speed was because the increased volume of air was able to keep up with the extra fuel that was dripping into the manifold? Does that extra fuel account for the bogging at lower speeds? I haven't had a chance to drive around yet since getting it to idle. Am I on the right track with what I'm doing? I don't have any diagnostic tools other than a Haynes manual. I do know about the paper clip thing. Before I unplugged the temp sensor I was only getting code 12 and no SES light on. I noticed the light on when I was idling it with the sensor unplugged though...sorry this is so long, I just wanted to describe the symptoms I'm experiencing and what I've done to try to correct things so far. Thanks for any advice!