check engine light comes on and stays on ... on 1994 Mazda B2300

after engine warms up ( 30 seconds) check engine light comes on AND idle drops down to 350 rpms at the exact same moment . these conditions remain thoughout the driving trip.

1 answer
The check engine light being on is telling you that the computer has detected a malfunction in the engine/emission control system. When the light's on there are data and diagnositc codes stored which can be accessed using a scanner, and there is history available..
Find a Mazda specialist to scan the computer and find out what's wrong.
Here's a directory link for you:
https://repairpal.com/directory?address=90803&car_brand_names=Mazda