Help! pitiful mpg on AMC 150 in my cj7

About a month ago I bought an 84 CJ 7 with a 4 cyl. AMC 150 engine. It runs good but seems to stumble or have a flat spot at mid rpm acceleration. It also gets TERRIBLE gas mileage.... 9 mpg !! Any ideas guys? All suggestions would be appreciated. Thanks

 

Jat, 9mpg with a 4cyl ??? What carb do you have?

 

if still stock, probably has the computer controlled YF 1 bbl.
but.....there are many, many possibilities here
engine tune-up condition? air filter?
axle ratio vs tire size?
0xygen sensor?
what is engine vacumm reading at idle?
mixture control solenoid?
trouble codes?
cement filled right foot?
I would have a competent shop anaylize the exhaust and the results
too rich is going to knock out the cat conveter very quickly and plug it...if that hasn't happened already
my two cents worth

 

It's all stock! It passed CA smog, and my mechanic said that it is running lean and clean out the tail pipe.