jocressm

I have a 1995 Grand Cherokee with 4.0 in it. I bought jeep nonrunning and installed a 96 4.0 motor in it. Runs decent down the road but idles funny. (i.e. up and down 2 or 3 hundred rpm) Starts cold fine but when it is warmed up i must give it throttle to start or it just cranks. I have done the easy tuneup but nothing else. As I look at parts I see a 1995 takes different fuel injectors than 1996. Would this be a problem? Does seem to have some hesitation when taking off like it is running lean. My jeep is full time 4X4 but gets only 13mpg. Is this normal? Seems pretty bad to me. Any help?