No, it does not idle rough at all, there is just a vacuum drop when put in gear. I went ahead and replaced the vaccum hose to the transmission modulator anyway with a new one. Now the vacuum gauge shows the lower reading of 15 whether in gear or not, it dropped with the new hose.
The vacuum will drop when the engine is placed in gear. Vacuum is load dependent. The greater the load, the less vacuum. When in gear the engine is turning the hydraulic system in the trans causing a load.
You must have created a vacuum leak when the hose was replaced, double check.
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