1998 Ford Escort Valve Adjustment

According to ALLDATA, if your vehicle is equipped with a 2.0L SOHC engine, it has no provision for valve adjustment.
P1131 Is an oxygen sensor related code, indicating the system is correcting rich for a condition. To answer your question, yes it could be caused by valves. Although, it would be more a mechanical condition as opposed to an adjustment. The list of causes is large, everything from a faulty air cleaner to a vacuum leak. Some of the more common faults may include an exhaust leak before the O2 sensor, a vacuum leak, rolled or split induction tubing after the MAF sensor, leaking EGR valve.

The wheel shaking when braking could be a sign of rotor runout, or worn front end parts.