I have a 91 Dodge Caravan with about 130,000 miles on it. It runs rough when frist started, the warmer the rougher it runs. But when driving it runs fine. So I replaced the plugs. The old plugs look worn, but the color was a good ashy gray drown. I drove about 250 miles on the new plugs, and a bottle of injecter cleaner, it started the miss at lowwer rpms like its getting flooded, if you step onit it comes out of it. Its just getting worse. I pulled the plugs there were black!!! All of them black!!! I put new plugs again it dosen't much better. Its spitting out black soot on the ground, and blueish smoke that smells like gas. Can anyone help???

 

Have you replaced the O2 sensor? Without any other information it sould like the O2 sensor sound like it could be bad. If so it will run a very rich mixture. But this is only a wild guess.