1989 190 2.6

I have a problem with my cars lack of power. When I start the car in the morning its fine for about 2 minutes until the cars temp hit 50, then the car hesitates. I have to pump the gas pedal up and down to get the car going. It seems like I'm pushing on air and the car isn't getting gas, but when the cars temp hits 80 the car is fine and back to normal. I can shut the car off and restart and it will be fine as long as the car temp doesn't drop below 80. It seems that anything between 50-80 on the car temp its not getting the correct fuel mixture. any help??
Took it to the dealers here is what I had done:
Replaced wires
Replaced plugs
Replaced dist cap
Replaced rotar
Replaced air flow meter (adjusted potentiometer)
Tested Fuel Pressure (system 80 psi, L/chamber 75 psi
Tested EHA current 20 ma key-on, 2-5 ma @idle, fluctuates w/accel-decel
Tested Lambda Control - good occilates
Tested Temp Sensor - 2.94 52@ 70F
Tested Fuel Volume - Good
Tested Fuel Sample - Good
Tested Both Fuel Pumps - Running
Tested Exhaust Back Pressure - OPSI @idle & 3000RPM
Tested Temp Sensor - Good
Tested O2 Sendor - Good, but is lazy EHA