Did you find the custom air-intake to be worthwhile?

We have a 91 f150 with the inline 6. It has the M5Od tranny. Our clutch was going out and we know it. When it did the pedal went clear to the floor and stayed there we had to put it in first to start it, and then could power shift it. Then while driving it all of a sudden it wouldn't come out of 1st gear at all. We quit driving it at that point and my husband also wanted to replace the rear main and the oil pan gasket at the same time. So he pulled the engine, did the seal, the gasket, and the clutch kit and slave cylander. There are several different recommended ways of bleeding the system and we've tried a couple of them. The problem is the clutch pedal doesn't come back up off the floor without you pulling it up. When you push it down it just seems to slam to the floor. We don't it's because of air in the system, or another problem. I hope you can help me. This is getting so frustrating. Thanks