Hardbody running rough

[outlawjoseywales]

New guy here, learned a lot on this site thanks for the help.
I have a 97 Hardbody KA24E engine. I've replaced all belts, most hoses, all vacuum hoses, O2 sensor and MAF sensor too. (along with lots of cosmetics)

It was running fine, although the gas mileage was questionable after the MAF was replaced. Last week, I added one 3" hose that didn't come with it, from the Air Cleaner housing to the Rocker Cover and it ran fine, although the gas mileage was still bad. The next morning when I cranked it up, it acted like it was running on 2 cylinders, badly. Finally after running it a while and getting up to speed, that stopped bucking and shaking, but it stalled at traffic lights and shut off. I had to recrank it and the whole misfiring and shaking started over again.

I went and had the codes pulled and it was a P 0443 (an Evaporative emissions EVAP canister purge control valve/solenoid valve) WHATEVER that is.

The guy at the shop said that it shouldn't be effecting anything, but I'm not sure he knows.

Please help, it's running badly right now.