engine cutout/jerking problem

I have a 1994 dakota club cab 5.2L v8. automatic tranny, 230,000 on odometer. on the freeway 4th gear 65-70 mph rpm reads 2300-2500 the truck starts to jerk like it is not recieving enough fuel. Kind of like you are driving a stick shift and you drop it into 5th at 15 mph. however if i step on the gas and the problem goes away instantly and the truck excellerates with out a hitch. has the the same problem in all gears at different speeds. 2nd gear 40-45 mph cruising, steady rpm. I have put new plugs (champions), wires, cap and roter, throttle positioning sensor, oxygen sensor, taken apart and cleaned throttle body. No check engine light is on (it does work though), transmission has been worked on and transmission people say it is an engine problem. I am running out of ideas, thinking possible map sensor next? Any ideas?
Thanks in advance.
John