Polyester Shirts

Not been on for a long while as everything was going smoothly....until I had to do some formal shirts 65% polyester 35% cotton. I thought that shirts would be a doddle....ha....Its a large design for the back, writing on top with disabled sign in middle and writing underneath. I did this on some polos and they came out brilliant, but on these shirts, there was a lot of puckering especially between each letter. I played with the density, the compensation, tried cutaway stabilizer, tearaway stablizer, iron on stabilizer, even used some felt as stabilizer! I got the best results and least puckering from the iron on, BUT, once washed, the stabilizer no longer was fixed to the shirt, and the parts that were still stuck went all bubbly. I've been stitching this out for the past 3 days now using the shirts as practice runs. I've run out of ideas now and have no idea what to try next. Can someone please tell me what is the best way to embroider on polyester. I would be so grateful for any ideas.
Thanks in advance.

Location: 
United States

First of all what needles are you using? You may want to try it with a smaller needle. I'm sure you should use a ball point. maybe a 70/10 instead of 75/11. If that doesn't work possibly double backing if don't have thick. hope this helps,jimmyg77777

Many thanks for replies, I use the hoopmaster so I don't think the shirts were hooped too tight. I didn't think about needles tho, I have some ball points so will try that. Altho the design is large, it's not really dense, and I took out the underlay too. The polos weren't heavyweight ones but not flimsy either. For now, I've given up on them and my customer is going for 100% cotton now, but I will experiment once I have time with the remainder of the poly shirts, think I've only got the sleeves left to play with lol but it would be nice to figure it out. Thanks again
mino

Well, I think I've cracked it. I remember I had some sticky stabilizer so I did a test run and it was much better so I tried again but also used cutaway stabilzer on the back. I also changed to a ball point needle. This worked fine, though I found it was even better once I cut the cutaway round each letter. A lot of bother but the result was good. If I'm asked to do polyester shirts again I will bumb the price up though!! I appreciated your replies. Thanks
mino