Problems With Intermittant Stareting

One Day My Van Didnt Start. I Had It Toe It To Service Station.
They Replaced The Starter, Relay, Ignition , All The Wires From The Battery To The Starter And Still, It Wont Start! The Check Engine Light Comes On. Sometimes By "rocking" The Van Back And Forth It Will Start. I Dont Have Much Mony Left For Any More Repairs. What Can I Do To Re Set The Computer Or Can I "hotwire" The Started Directly To The Battery? Help!!!!!!!!