Check the plastic hose that comes off the vacuum pump (the metal housing in front of the mechanical fuel pump) as it likes to split. If the brakes are solid, i.e. no servo assistance, then it does sound like a huge air leak to me, hence the crap running.
As for the dash lights, you gotta be careful pulling the battery on these cars. They don't like it. Pull it again, but leave it disconnected for 30-60 minutes this time. I had a situation recently where pulling the battery for 5 mins took out the driver's side door module when reconnected. No petrol flap, no central locking, no pump priming, no electric windows, no dash board door open warnings....nothing.
Thinking a wire in the door loom had coincidentally snapped, I dug around in there for ages. Checked fuses etc, all good. Pulled the battery again and left it off for an hour and bingo, everything back to normal. Stupid cars