I have a 1991 F150 5.8l. It has developed a miss on acceleration and under load. Check engine light comes on intermittently. Codes are # 33, 34, 41(bank one). I have replaced the EGR valve but still getting the error code. Could it be the oxygen sensor or EGR sensing unit?

 

Might get more responses in the pre 97 forum. this is mostly for the modulars.

 

How does the rotor look in the distributor?

 

Rotor was pretty corroded as were the contacts. I cleaned them, changed a vacuum line, the 02 sensor, and spark plugs. Still has a miss.

 

I would change the rotor, distributor cap, and plug wires.

 

This. If the rotor was corroded, its probably safe to say the contacts are getting short on it as well, and replacing the cap and plugs with it is just good maintenance.