1991 Mustang GT, Malfunction in Instrument Cluster

[chozenfew805]

I thought my idle was at 1800rpm so I did the idle checklist and took care of some vacuum leaks but I could only get it down to 1500rpm. My car sounded and felt like it was below 1000rpm when idling so we hooked up a digital timing gun with a built in tach. It turns out that the car idles fine at 850rpm, but the instrument cluster says 1500rpm. I'm going to check for intermittent connections on the distributor and the cluster but does anyone have any other advice on where to start?

 

[seijirou]

I thought my idle was at 1800rpm so I did the idle checklist and took care of some vacuum leaks but I could only get it down to 1500rpm. My car sounded and felt like it was below 1000rpm when idling so we hooked up a digital timing gun with a built in tach. It turns out that the car idles fine at 850rpm, but the instrument cluster says 1500rpm. I'm going to check for intermittent connections on the distributor and the cluster but does anyone have any other advice on where to start?

you sure you don't have a 4cyl tach stuck in your cluster?