Mazda b2200 1990

Where are the screws on the carb to adjust fuel and air mixture black soot comes from my exhaust. The truck idles at about 600rpms and the truck sputters. Does anyone,know a link to a stock carb for the truck.

Is the choke all the way open when this occurs? Is the smoke gray or black?

I found the air mixture screw doesn't really smoke but oil comes out of the exhaust

Check compression, probably the rings. The oil rings gets sludged and stop wiping the walls down, but what you got a coupla hundred thousand miles on it?
Are the spark plugs oily also?

Spark plugs are oily I bought it with 234k, what do you recommend I do I love the truck btw lol.

I'm sure everyone will tell you I am partial to the 4.3 (right away jump to 190 hpr.) GM Vortec, truck engine (Astovan has stuff too high on the engine) because it is the only one I have done in a Mazda. I did it because it looked like an easy swap. I mean, I put a 350 four speed in a '77 Vega Sedan Delivery Wagon in '84. That was interesting, and others along the way.
The 4.3 automatic is as close to a drop in fit as it gets, probably. The motor mounts sit on the original mount pads in the truck. I went with a carb and '86 HEI distributor.
I think there were only three mentionable modifications, the cross member under the oil pan, the driver's side exhaust manifold and redesign the shifter. Truck looks original. Of course have to fabricate engine mount saddles for 77 GM engine mounts, fabricate transmission cross-member, transmission shift leaver and drive-shaft.

Yeah not really going that far plus I like that it's a manurl.

Not sure about a manual change over, shift location. I have a 5 speed, but did not go that route, with 70 horsepower increase.