heater not working,service engine light on,running rough on 1992 Ford E-150

Just got the van and the service engine light was on,no heat,running bad especially at idle and dying when i put it in gear,did a tune up,changed the water pump,changed the thermostat.Test drive-imediately the service engine light on,heat started working then stopped,and then over heated bad????

Asked by for the 1992 Ford E-150
The light is on for a reason, you will need to access the on-board computer and see what codes are stored to be able to address this.