smelly exhaust!

[grt]

Having some issues with my 05 Uplander, its over heated the past 2 days in the morning and then later in the day its fine. I did replace the thermostat not to long ago, also getting a code 301 again(had same code 4 months ago and ended up replacing coil pack, plugs, wires, and #1 cyl fuel injector before it finally solved the problem) now its back again, and the exhaust smells really bad. Im hoping its not a head gasket or cracked head, doesnt seem to be using up cooland, i had to add a little bit

Help please!

[Tech II]

A misfire dumps fuel into the cat and can cause the smell.......needs to be fixed or you will need an expensive cat....