Ford Repair: 1991 Ford F-150, ford f 150, diagnostic port

Question
Our ford is having some trouble.It recently had a new computer installed and now it will start but it will stall at most times when gas is applied.It only started two days ago and was driving fine for 3 months after the computer installation.The check engine light is on. It is a custom crew cab I believe.I don't know what the engine size is but it has 321,000 km on it.

Answer

Diagnostic port Retrieve the engine codes. Instructions are in the aftermarket vehicle repair manual by Haynes. It is available at most if not all parts stores. Odds are, that your new problem has nothing to do with the current problem. I have attached a picture of the diagnostic port located under the hood.