Anyone have suggestions before I dig into it for the following? The truck is a 91 B2600i 4x4.

Starting the truck after it sits for a few days results in one of the lifters clicking for a while until it is at operating temp. If driven daily it is fine. I installed a reman head in 12/06. This issue started a few months ago. I'm thinking of an engine oil additive to add at some point before doing an oil change. There are so many I'm not sure which one.

Also after sitting a few days it will sometimes run on 3 cylinders, usually less than a minute. The missing cylinder will start hitting then eventually it will be fine. I've done the usual: new plugs, wires, distributor cap, rotor. I'm thinking maybe an injector is gummed up. I'm thinking about one of the concentrated fuel injector cleaners. Which one? So many to choose from.

 

try some sea foam