My '98 TJ 4.0 recently started missing a little when cold. At the same time, the speedo started to "wander" +/- 30MPH or so, and occasionally "jump" all the way until it hits the trip reset shaft. I know, I know, "fastest jeep ever" ... I pulled the instrument cluster, cleaned & "twisted" the connector contacts, etc. No improvement. Given the simultaneous engine troubles, I am now thinking it could be a grounding problem. Any thoughts? Advice on grounding points to check/clean? Thanks!