Sounds as if it's got generally damp when it's been standing. Clean the spark plugs, dry the plug leads and try WD 40 on all the HT side of the ignition to cure the misfire. Check underbonnet and under dash fuse boxes for damp to see if that's the indicator problem. Otherwise, check the earths on all the light units - it may be that one light is earthing back through the indicator circuit.
Hope that helps
Tim
In case you haven't solved this yet, the MIL I think you're talking about is the engine management system warning light. This is controlled by the engine management computer, which turns it on when it detects that readings from one or more sensors is not what it expects. The computer also (conveniently) stores information about what the fault is in the form of a code. A garage with a standard EOBD code reader will be able to plug it in to your car and get the information about the fault (EOBD stands for European On Board Diagnostics). The faults are usually poor connections or a faulty sensor.