With an '89 bronco all you need to pull diagnostic codes from your computer is a 4 inch pice of wire and the ability to count to ten.
HowTo pull OBD 1 codes in your driveway
In this little tutorial, I am not kidding when I say to check for vacuum leaks AND your coolent fluid level.
let us know how you make out.
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BroncoJoe19
2006 Alt Fuel Jeep (electric)
'98 windstar 3.8L
'99 Crown Vic 4.6L
'90 Full Size Bronco 5.0L
I'm not a professional mechanic, take my suggestions with a grain of salt, or a cup of coffee