Pontiac 6000 stalling at lights, idling

Hi there! I have a 1989 Pontiac 6000 wagon. Lately she’s been stalling when at a red light or otherwise idling too long. This problem came up a couple years ago, and we put in a new battery. When it continued, we found that the horn fuse was draining the battery even when the car was off. The mechanic put in a workaround wiring that bypassed the fuse box, and this seemed to help. It started up again recently, and seems to be aggravated by having the turn signal on. It also is worse when the radio, wipers or headlights are on.