Betsy's Idle Problem - E150

Hello Group!
I have a 1988 E150 2x4 Limited-Slip Wheelchair Van
She was converted as new into a Quad wheelchair van, 1n 1987.
In 1996 with 97,000 miles her original 302 was replaced due to a burned-out
valve et al. I figured I might as well replace the entire engine. It was lacking power anyway. I had a high rise cam put in for more power. A stock 302 wasn't powerful enough. The cam made little noticeable difference if any.
In 2004 a similar problem arose at 177,000 miles and I had a 351W with a high rise cam and dual exhaust installed.engine number 3. She's got plenty of power now. It's a Jasper rebuild with the original fuel injection from the 302 Betsy came with.
THE PROBLEM:
At a cold start; she starts fine, but as she warms up the idle lowers and she stalls-every time. When I restart her she's okay.
At a warm start (after 15 minutes or so) she stalls.
This has been going on since quite long ago-even with the previous engine(s). I thought the problem would go away with the new engine, but it's still there.
This is a real pain in cold weather. What could it be? The mechanic thinks it might go away as the computer gets used to the new engine. She did sit for a few months and the batteries went dead.
Any suggestion would be appreciated.
Thank you.
Best regards -Brian Bard snipped-for-privacy@comcast.net
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Love Revolvers opined in

Organize your thoughts!!!
This happened with both 302 and the 351... but did it happen with the original cam?!!!!
The mech is technically right but since the computer never learned before, why would it learn NOW!!!
And NOW you have an engine with parameters at the very edge of the 302 ECM's capabilities? I wouldnt be surprised if you blew yet ANOTHER Exhaust valve.. that's what it was, right? Because you added more than 10% displacement/air flow and didnt even upgrade the injectors for 10% more nominal flow
And Quit looking for easy fixes from a cam... Ford didnt put those original cams in there for economy!! It's a truck, remember!
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Love Revolvers wrote:

Aside from your EEC problem, you have gone the wrong way with your camshaft selection. What you really want is an RV/towing grind, not a "high-lift" shaft. The early 5.0 GT camshaft, a marine grind, would be a suitable factory substitute for non-roller blocks in the 302 or 351. For roller blocks, you will have to do some research, I think the GT cam is a bit much for the low end you are looking for.
Rob
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