Sounds like a vacum problem still... as vaccum opens and closes the doors...
Check the line very closely from the engine back to the firewall.. had a few burn on the exhaust manifold and one where the vaccum resevoir (what holds the vaccum) was cracked and wouldn't keep enough vaccum to run the doors...
But my vote is check for a gray line broken (burned) by the right exhaust manifold in the front of the manifold (right behind the alternator or so if I remember)
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Cargo Liners
