Hello Andres and welcome
My truck is a California emissions 1986 2.6L 5 speed stick 4x4
The Mikuni carburetor was the cause of rough running but then I finally rebuilt it during the long covid pandemic shutdown...
Please check out my profile, photo albums & posts ~ maybe they will provide enough info for you to get your truck running well...

Many folks here will recommend swapping the Mikuni carb for a Weber carb but not me ~ it was enough of a challenge (and money) just to rebuild the Mikuni... I dunno but I really doubt that changing to any other carb or fuel injection system will be worth the hassle & money and the results won't be much different that what the Mitsubishi engineers designed into this vehicle...

I am happy with a rather CHEAP smooth running small truck that can keep up with traffic... If I was gonna invest hard earned money into a motor vehicle that is not really safe to drive fast or survive a violent collision then I would have to ask myself WHY AM I DOING THIS..? AFAIK these trucks don't even have crumple zones or air bags or anything else that could prevent death in a high speed crash..!?! The $600.00 to $1,200.00 to invest in a Weber carb will not result in any BUTT-O-METER results worth the trouble 'n effort 'n expense... But, I really dunno coz I never went that route...

Happy Holidays
George