I have a 98 with the 5.2. Replace the heads no issue going back together. Replaced broken, damaged and worn out vacuum lines. Has no vacuum leaks. But truck still Boggs down and tries to shut off at take off unless you let it start on it's own and then ease on the gas. Is idling a little low but steady. No engine codes

 

What was going on with the heads for you to replace them? Any burnt valves? Once up to speed, does it act normally and you can accelerate as you’d expect?

 

How long was it down to be repaired? Is your exhaust free flowing? Hook a vacuum gauge to it and see what kind of reading you pull. If it's low, you may have a blocked exhaust. A melted cat converter or a cheese thief might have built a nest in the tail pipe.