1995 Ford Windstar lighting problems

I asked the seller at ford to completely service the van before I would buy it. He said his mechanic would. I checked the van out two weeks later, low on oil, no brake fluid, trans fluid very low, no water hardly at all in receiver, then the starter went out, replaced it no good, replaced switch, no good, brakes gone out, can't keep fluid in systems, engine light came on, emission problems, mechanic stalls for the hour amount, and still can't fix/test II code. Inside lights dim when extra. Lights come on.

Speedometer inoperable above 45 MPH (bounces and grinding noises); outer door locks inoperable (except drivers door), key only opens drivers door; door ajar sensor and interior lights stay on when all doors are closed.