I seem to have a problem with my turbo, i thnk, car starts fine but engine r.p.m. and turpo gauge higher than normal when idling [about 1and a half] instead of below 1 on the r.p.m. guage. neutral its much higher revs and driving down the road I dont even have to put my foot on the gas and car will travel down road at about 40-45. If I continue to keep foot off gas r.p.m. will drop slightly below 1 and a half and then kick itself back up to around 2 without my intervention. All these erratic r.p.m.s ,not to mention being tough to hold car back with the brakes is a real pain It's a 740 Turbo Wgn. 1987 with 193,000 on it and runs great otherwise. Please,can anyonr offer any ideas on what the problem might be?