Ford Repair: Surging motor, crossover pipe, ford f150

Question
I have an 88 Ford f150 with a 302 efi.  i just replaced the upper gaskets and when i idle it starts fine and then after it warms the motor starts to surge,  The idle becomes sporadic. it goes to the point of stall and then to 1500 and back.  When I have it in gear and there is load the idle is around 750.  This is driving me nuts.  i have also replaced the in line valve on the top of the crossover pipe.  This is when the surging increased.

Answer
Hello and thanks for the question...I'll try to help.
 I would suggest that you reset the idle strategy. To do this remove the neg battery cable and wait for 10 minutes. reconnect it and then disconnect the ISC motor wires. Now start the vehicle and adjust the idle until you can get it to spec. idle in gear. Then shut it off, reconnect the ISC motor, and restart the engine. Drive the vehicle for 10-20 minutes at different speeds for 5 miles.
Hope this helps,
Erik