The van was running ok than it started stalling. I thought it was out of gas. I went to take the gas cap off and all this pressure came out. Than it ran again. Than the next day I started driving it and it did the same thing it started stalling out. I took the gas cap off and it had all this pressure that came out. So I left the gas cap off and drove it home. When I put the cap bk on and start it it still builds up all this pressure.