1988 E-350 Chassis (7.5L) Motorhome

[CygnetAtlanta]

I recently purchase an 1988 RV which is built on a E-350 Chassis (7.5L EFI). The day that I test-drove the vehicle, the battery was dead upon arrival. The dealer jumped the engine, it started right up and it ran and drove perfectly. I left a deposit and instructions to replace the batteries and a few other things. The following day when I picked it up, they had replaced the batteries (one for starting, one for house battery). The vehicle stalled immediately upon starting up. The dealer explained that becuase the battery had been disconnected too long while changing them, the computer was zero'ed out, and that it would get better as I drove it (i.e., it would relearn its settings). It ran very roughly on the trip home, the max speed was about 30 mph, and it was chugging along down the interstate. I had it towed back to them the following day for service. They replaced the catalytic converter and told me that the problem was resolved. I went out and picked it up, and when I got it home, it stalled out again. Note: The vehicle only stalls out at low idle when there is no load placed on the engine (i.e., vehicle in park, just idling). It might be noteworthy to state that when the vehicle is in gear (such as stopped at a red light), it doesn't stall out. I took it back to them again, and infomed them that it was not fixed. They took it back in and said that they couldn't duplicate the issue. I drove it about 5 miles, then brought it back and was able to duplicate the problem for them, in their presence. I told them that I thought the problem was the fuel filter, as I had already had the throttle-body and associated items cleaned by a mechanic. I thought this because it will only stall at low idle with no load on it. The dealer then said that they were not able to diagnose it and sent it out to an outside mechanic for repair. The mechanic is replacing the computer to resolve the problem.

So my question is, do you think that this will resolve the problem? I bought it on April 15, and have actually had it in my posession for less than a week, and I'm getting frustrated. The RV dealership has been decent and they are trying to fix it the issue, but are they going in the wrong direction? I've been told that 1988 was the first year that they offered the 460 with fuel injection. I'm not very knowledgeable about it.

Thanks!