I have a 1990 Sunbird 228 Barletta with a 5.7 OMC engine and I'm having trouble getting the engine in neutral. I have adjusted the shift cables to make sure the interrupter switch was properly aligned and even replaced the switch. Once I did all that it seemed to fix the problem, but after 30 min of running it does it again and I can't get it out of gear unless I quickly killed the engine by turning on and off the key. I then manually tripped the Interrupter Switch at the engine and got it to work by jiggling the wire harness. So, I cleaned all the connections and that worked for about 1-2 hours. It started to do it again, I repeated the cleaning process and I cannot get it to work unless it sits for a while or cools down...does this sound like a ground issue?