Is the 70mm throttle body larger or smaller than the factory original? What else would you recommend that I change that is a part of the throttle assembly as I make this change? My truck is all original, 69,000 miles and it runs perfectly when cold, after the engine warms up, it seems to flutter with steady highway driving. It is not electrical, seems to be more air/gas mixture.
The stock throttle body size is 65mm so this will be an improvement over stock. The kit comes with everything needed to do the swap. No other additional pieces are required. Upgrading the stock air intake filter is a popular mod to compliment this swap, and for that we recommend part number KN-572517. As for your flutter issue, I would ensure all maintenance is done. Things like fuel filters, spark plugs/wires, ignition coil/distributor cap, even improper timing can cause symptoms like this.