Yesterday I changed the plugs in my car because it wasn't runnin quite as well as I would like and I thought they were the culprit, turns out two of them were in finger tight and not sealing at all, previous owners fault, anyway I put in AC CR43TS as recommended, started the car up and it idled not too bad, as soon as I put the car in hear it stalled, started it up and went for a drive, seemed that any time I pressed on the pedal with any force and put a load on the motor it would cut out and miss etc. In park revving the engine it seems alright, I'm wondering if I didn't disturb the wires enough when I changed the plugs that now they won't fire under load? The car had sat for two years before I bought it so maybe they broke down enough in that time ?