cutting out

I have a 1991 Jeep 4.0 it is cutting out at about 2000 rpms, I can smash the throttle down it will pick up and go but as it gets hotter I cant get it to go over 10 - 15 mph, I checked fuel preasure and I'm good there I'm preaty sure its spark thinking it may be my pick up coil does this sound right? and what else could posibly it posibly be

Thaks for your help and time

mines doing a similiar thing.. and i'm still trying to figure it out... when she's cold she's fine.. after she warms up... she cuts in and out

I have had a couple people tell me to change my 02 sensor, so this weekend I'm going to try that unless I have to work I'll let you know if it works