B2000 Stall at idle

I have just put an 89 engine in my friends 87 B2000 and it run great, but after running at idle for a few minutes the check engine light comes on and it just dies like I turned it off. It starts right up and runs good and then dies again after a couple of minutes. The vacuume guage reads good and the timming is good. Does anyone have any ideas on what to check?

Thanks.

Pull the computer fault codes to find out what's causing the check engine light to come on.
Go to http://www.avproecm.com/ on pprocedure how to pull mazda b2200 computer codes.

Did you use the b2000 carb or the b2200 carb on the 89 engine?
I think they have slight difference in vacuum lines and computer wire connections to the carb.

Have you checked the idle and choke adjustment on the carb?

Let us know what you find out.

I restarted it tonight and set the idle a little higher and it seems to be running pretty good now. I let it idle for 15 minutes and it seemed ok.

Thanks for the advice.