I just started having an issue with my '01 Ram today. When I am at higher RPM's (2500 RPM +) it starts to stumble like it's running out of fuel even though I have over 3/4 tank. Then every so often it won't want to climb over ~2200 RPM and it will dump out light gray/blueish smoke. I haven't taken a look under the hood yet because it was too hot when I got it home. Any ideas?