The engine idles roughly but does fine at higher rpm (2000 plus). The check engine light has come on indicating a misfire in cylinders 1,3, & 5. It also indicates a malfunction in the EGR valve. I found a vacuum hose that had become unattached from the filter housing and reattached it. This did not immediately fix the problem, but after about 15 minutes of driving the car was running perfect. A couple of days later the rough idle came back, but the vacuum hose was still connected. Would a bad EGR valve cause problems only in cylinders 1,3,5? or do I most likely have another leak somewhere else?

The engine idles roughly but does fine at higher rpm (2000 plus). The check engine light has come on indicating a misfire in cylinders 1,3, & 5. It also indicates a malfunction in the EGR valve. I found a vacuum hose that had become unattached from the filter housing and reattached it. This did not immediately fix the problem, but after about 15 minutes of driving the car was running perfect. A couple of days later the rough idle came back, but the vacuum hose was still connected. Would a bad EGR valve cause problems only in cylinders 1,3,5? or do I most likely have another leak somewhere else?
pull vaccuum from the egr.if you car dies then the egr is ok. if not then replace the egr