I'm seeking advice from the congregation. I have stock, very mild cammed 350/400 combo in a friends truck that I’m working on and I can’t seem to find a culprit to my issue. My issue is that when I shift from park to any drive gear it revs up slightly, slams into gear and stalls. I have to work the brake and skinny to keep it going and when I mange to get it in gear without stalling it feels like it has a lot of load on it as well. I couldn’t find any vacuum leaks, and everything seems to be getting vacuum from the proper location. The engines makes 18hg. The converter feels stock-ish and is to the owners knowledge. The trans fluid is fresh and so is the carb. The engine runs good otherwise. I'm leaning toward the converter but have never experienced this before and wanted to double check with you guys before I drop the trans. Thoughts?