2000 Corolla a/t with add on Rostra vacuum cruise control. The cruise control worked fine for 20k miles on this used car then started cutting out. Would hook back up for a while then would cut out again. Finally quit altogether. Tightened up connection to throttle on advice of friend. That helped but now it only stays on cruise for aproximately 5 seconds then cuts out. If I press resume/accel it will work for 5 seconds then cut out. That is consistent. If I hold resume/accel it will cruise at current speed until I let go. Any suggestions?