BMW Repair: 1986 BMW 325is, wire insulation, bmw 325is

Question
Hello there firstly id like to say my engine is runing just fine when it runs,what happens is while driving the car randomly cuts out then after waiting a few minuets the car can be started only to cut out again at randome,this problem started after driving on a very bumpy road and it had rained alot that evening.at firt i thought it was fuel filters (found some rusty paticals),so i changed them and put enjector cleaner in the fuel but the problem persisted ,so i then checked the airflowmeater which seems fine ,and iv just recently discovered that as the car starts to cut out ,if i slap and bang on the dashboard  my car starts going again which leads me to believe its electronic,any advice or help would be highly appreciated pleas and thank you very much for your time.

Answer
First thing is you should do is not to bang on the dash as I don't believe your doing anything but taking a chance of cracking the dash pad.What you need to find out is when it stops running is why.Is there spark? If there is then the fuel is in question.Your problem probably is the lack of spark or you loose all DME function.You probably have dirty connections.You should clean all the battery connections as well as the relay terminals need to be examined for corrosion(green). Checking the wiring for corrosion is a little harder but can bee seen as bumps in the wire insulation.Check all the relays near the fuse box for corrosion as well.