97 Silverado intake 5.7

Just did an intake on 97 silverado 5.7L

Truck fires up but the rpms bounce up and down 500rpms like 1000 to 1500 to 1000 to 1500.

Any ideas?

distributor seems ok. TDC #1piston the rotor is pointing to #1 on the cap and the rotor is pointing to the 8 on the distributor housing.

I could be wrong but it sounds like you have a vacuum leak. Try spraying WD-40 around the intake area and if it smoothens out, that is what it is. Also double check to make sure you have all the hoses re-connected.