excessive smoke

[kustomizer]

i am getting excessive smoke when i give it throttle it will finally go away but if im towing with it it takes it awhile to clear up like it is getting to much fuel i get a service engine light comes on and off but the codes show it to be a evaporator pressur high and low any suggestions and sometimes it will hiccup a little then take off anyhelp would be appreciated thanxs this motor only has abot 25000 miles new gm motor

[grancito]

Please fill in your signature so we know something about your truck. I know it is a 94 and evaporator code doesn't exist, post the code.