92 sl

problem: when slowing down, push the clutch in, oil pressure gauge shoots to high, rpms drop to zero and car dies. sometimes the car will start right back up, other times we have to let it sit for a few minutes. either way, when it starts it will run fine for about 10 minutes, then when we slow down it goes thru this cycle again. clutch in, oil pressure sticks on high, rpms drop to zero. any help would be appreciated. replaced the positive battery cable and the egr valve. thanks