1989 Cadillac Hearse map sensor

We did a tune up on my caddy and immediately check engine came on. We had it tested. Said map sensor went out. After 3 weeks to find RIGHT ONE and had to redo map sensor AND redo new harness. The light STILL comes on. We undid the battery for a half hour and put it back together and lite STILL comes on and runs worse than ever. Idol off or timming. Any suggestions? I need help