The rear latches on my V4'rude would rub through the boots on my plug wires. When latched down they would ground out the cylinders. It would run fine with the latches unhooked. I would check to see if the boots have a crack in them.
Had the same problem Yepblaze described on a merc. The motor mounts sagged and exhaust escaped into the engine compartment.<br /><br />If they run OK on the hose (with hood on) then I'd suspect exhaust leak.<br /><br />Let us know.....this is interesting!<br /><br />Also, do both engines have the same problem?<br />Do they both quit when one hood put on?<br />If they do, I'd be looking at a common kill circuit getting grounded.....<br />