We removed our old tub/shower and put in a new shower stall only. We moved the shower to the opposite wall and had to move some plumbing and the sewer hook up. The couple times we used it it worked fine. Now it drains very very slowly. This is what we did. We moved the shower drain approximately 3 feet, installed 2 in. ABS drain and p-trap with a 1/4 -3/8 in. drop per foot into the existing plumbing. We tied into the existing vent which was there for the tub. Do I need a vent closer to the shower or before the shower?

At three feet your vent falls within code. Are there any 90's in the drain line? Is it possible that mortar or some trash fell down the drain during installation? Regards, Tom

We removed our old tub/shower and put in a new shower stall only. We moved the shower to the opposite wall and had to move some plumbing and the sewer hook up. The couple times we used it it worked fine. Now it drains very very slowly. This is what we did. We moved the shower drain approximately 3 feet, installed 2 in. ABS drain and p-trap with a 1/4 -3/8 in. drop per foot into the existing plumbing. We tied into the existing vent which was there for the tub. Do I need a vent closer to the shower or before the shower?
With water in shower, use a plunger, fast and slow to see if you can tell anything. Any open ends you can plug in sequence may help give a clue. Check behavior of adjacent drains while you're plunging. Something's got to give.

At three feet your vent falls within code. Are there any 90's in the drain line? Is it possible that mortar or some trash fell down the drain during installation? Regards, Tom

Thanks for your help. It turned out that that is just what happened. We ran a snake and pulled out some insulation. We are free flowing now!!

With water in shower, use a plunger, fast and slow to see if you can tell anything. Any open ends you can plug in sequence may help give a clue. Check behavior of adjacent drains while you're plunging. Something's gotta give.

We tried the plunger option and it didn't seem to change anything. We ran a snake and pulled out some insulation. Works great know. Thanks!!