Electrical problem
1980 Volvo 245 4 cyl Two Wheel Drive Manual 178000 miles

About twice a year the fuel pump fuse blows, it seems odd in the fact the fuel pump wire comes out of the firewall and connects right to the battery, the fuse is in-line. Lately for some reason I'll be running errands and the battery dies when the car is sitting in the parking lot. Have had a number of mechanics look into it and cannot the problem. The last time I had it out was on the way home it started missing and then just lost power, had it floored and could only attain 5MPH, suddenly it kicked in. Have had the car in garage since then afraid to use it!!! Do I need a new fuel pump?