Mk5 will be easy to convert to PS.

The Mk 5/6/7 1400cvh Escort and Orions had all the brackets, pulleys and pump with all the pipework and resevoir and the steering rack fitted so just look out for a smashed car or the bits on ebay. Everything will be a reasonable straight forwards fitment.

Running issue I would presume to be a leak in one of the induction hoses or the breather system so have a good look around all the pipes for the induction system and breathers for splits and damage. If you can't find anything, get a tuner to check it over and set it up.