Hi late night car emergency

Hi, I'm having a late night emergency with my car. I'd appreciate anyone helping out and would be very greatful. It's a 96 Mitsubishi Magna SE and so far I've had no probs, had the car for about a year now and am up to date with service. I'm a bit suss on my latest mechanic though, as I've had to change from my old one due to a move, and I'm not sure the new one is checking everything. It has about 95,000 km on the clock. I've had some trouble with the lights being dim, which the mechanic didn't help any, and a mate suggested I unplug the battery, give it a clean, and plug it back in. The engine light was staying on a bit too long when I started the car (normally all warning lights light up the go off) but not at all while driving. When I reconnected the battery, and started the car, it started up, then dropped out. When I drove it around the block it would go fine until I braked or slowed, then the engine cuts out. I need to get to work tomorrow, and I would really appreciate any advice. I have a feeling it's something simple but I'm not very good when it comes to newer models. Thanks in advance, I really appreciate anyone taking the time to read this and help out.