I have a 98 ML320 we have changed the fuel filter And a pulley. It drove for about 30 Min. And it was missing a little. we figure it was injecters. so we changed them. Now it will not go up a little hill and most of the time it stalls. It also has a missfire on cylinder#4,#5 and #6. so we changed spark plugs And still has the missfires. Please help

Poor fuel pressure can cause the misfire code. Have the pressure checked. If it is fuel pressure the first thing to verify is that you had the filter changed to the new model. If not you need to have this done. I think that there was a recall on this item.

The next item is likely the fuel pump wiring. There have been a number of reports of defective wiring, some inside the tank. If the pump is failing you will need to replace the fuel pump as this is not an item that I consider safe to repair.

If fuel pressure is fine then it is in the ignition. Switch modules on the engine and test whether the problem follows the module. If not then it is the wires. If they are still original it is time to change them anyway.