Onan shuts off while driving/hot

I had a similar issue with my 1999 Holiday Rambler on the Onan 5500. I tried to solve it many times, but was unsuccessful, however after changing out the oil pressure switch the problem seemed to be reduced but not eliminated. Maybe the additional heat caused the oil pressure to spike? I know that on my newer Tiffin coach, with an ONAN 7000 aboard I haven't seen this problem as yet. This unit has an engine cover which is easily removable. If the purpose of this insulated cover is primarily to reduce noise, maybe removing it in ver hot weather might circulate more air around the engine. Just a thought.