Okay, so I'm going mad with this car now. Last week the car started randomly stalling after hunting a little whenever I pumped the brake a few times while rolling slowly when stuck in traffic. Got the car home eventually and half a dozen stalls later and the next day changed the spark plugs and sprayed some carb cleaner into the air intake and top of the throttle body. Car would stutter a bit and hunt a bit more before levelling out.

After running for a little longer the EPC light came on along with the engine management light. Had a friend to read the code and got P1553 Barometric/manifold pressure signals: implausible correlation. That's my first issue, any ideas about how to sort that out?

Secondly, after resetting the lights both EPC and EML light went out but what I noticed was that the issue with the brake when pumping it around 3 times the car would hunt again and occasionally stall, it would also happen if I flicked on the heaters or another electrical appliance. That then causes the EPC light to come back on. Logic was telling me it was electrical issues but noticed tonight when I started the car up cold that the EPC light was out and even pumping the brake a lot and flicking the heaters on and off caused no problems with the car. No hunting and no stalling. Great. But then when the car started to warm up while driving it kind of lurched and on came the EPC light again and so started the hunting and stalling again when using the brake/heaters. Any suggestions would be welcome and any questions to clear up some of the details too as I know I've written a lot here and it can be a bit confusing. I'm writing this on the back of being completely bamboozled by the motor!