I’m having a weird intermittent starting issue. It began with hard starting having to floor accelerator to get XJ to start progressing to barely cranking over and not even getting a jump from tow truck to turn it over. My tech said bad battery cell. Bought battery 6 months ago. Take back to place I bought it for test. 1200 cold cranking amps. Store gave me post shims. Put them in and reconnected battery. BANG! Started right up! For 3 days. Then the whole hard start pedal to floor thing started again until no start. Let XJ sit for 3 days. Tried again and BANG! Popped right off! What’s going on? Has a demon possessed my XJ?