Some shops are reluctant to take on an intermittant problem I've found.
On a Safari was an intermittent engine rough run, and after changing out plugs, wires, on and on computer, found a cracked wire on the pulse distributer. Every time we worked on it, we jiggled the wires and it would run better for a while. So $1200 later its fixed. This is a 1992 unit. worth about $1000.
Some of these cars look like new, and are low mileage and very good bodywise and mechanical, but are a total loss , re expensive electrical repairs with no guarantee of success.