Idle keeps rocking and dropping

[brandontylerrrr]

We did a motor replacement on my '02 4.7L, after the old motor in the truck sat still for two years. The new rebuilt motor is running now, but it has to roll over twice before it fires up, it is idling at about 550 rpms, and when I slow down or come to a stop, the rpms drop from 1,000 to 0 and the motor shuts off.
I was under the impression it was Fuel Pump due to old fuel built up, but I dont know. Can anyone give me their thoughts or opinions on this matter?

 

[dapepper9]

02 is only in the 2nd gen section because some came with the 5.9 v8. 4.7s are 3rd Gen engines. Maybe a mod can get it moved

However, i will say this: unless you're like me and ONLY put in ethanol free gas, start off by draining the tank. Any ethanol will attract and absorb water. Actually since it's been sitting for 2 years, drain it regardless. Even today's regular gas doesn't stay good like it used to back in the old days