Hopefully the codes won't reappear. I've known my mechanic for years and he runs an honest business. Not to say that the codes won't come back. Hopefully they won't. Before he did the tune-up & repair, I mentioned what I read on this forum, but he was sure he found the problem at much less expense. He did say that the plugs on the van were the original ones (yikes) and I don't know when the fuel filter was last changed (purchased it used). It has 61K miles on it now, so it very well could have been the filter itself. I had a full tune-up done with new plugs, plug wires, fuel filter and a fuel injection cleaning. I've already driven 900+ miles on a trip and no light has come back on thus far.
As far as the ABS system, the van needed a new brake control module which was a $400 repair. Hope that amount is fair.