stalling jeep

Hello all , I need a little advice. I own a 1994 Jeep grand cherokee laredo with a straight 6 in it.It has 194,000 miles on it I have not had any problems with it other then routine maintenance but In the last month it has started stalling. Sometimes i will be going 60mph sometimes i will be going 20mph , The rpm's just drop out , sometimes it will go back up without stalling but 9 times out of 10 it will just drop and stall , after it stalls sometimes it will start right back up , sometimes it will not. sometimes it will start right up in the morning after sitting all night and sometimes it won't start. It has been given a full tuneup(oil change, new plugs,wires,cap,rotare) The fuel pump is working , it has been to the shop and the guy cleaned out a valve but it is still doing it. I am very frustrated because all of my gauges are fine , my computer isn't telling me anything and my check engine light is not comeing on at all.........HELP ME PLEASE!!!!!!!!!!

Please find the correct forum to post this in. You will get much better answers there.

http://home.comcast.net/~ec437/obvious.JPG

thanks for letting me know , i am new to this