35 to 45. Does it surge like it's running out of gas, or some one is turning the key on and off? Swap out the fuel filter if it's never been done that you know of. It's on the frame, drivers side frame rail, under the bed. That will reduce 1 possible problem.
Next how many mile are on it, has the timing belt ever been changed? You might want to look at the cam to crank timing. It also sounds like the choke system might not be working correctly. Does the choke flap open when hot? If it is then there is somthing keeping it at a high idle. 1200 is normal for cold start. 8 to 10 deg BTDC. There is somthing strange going on. It will just take a little time to nail it down, but don't give up. You will win.