Hey, thank you very much guys for your greetings. I am really pleased that my little piece of source code did something useful. I have been out of this forum but I am back. First of all, when you have a problem with this sound module, 90% of the times, blame the uSD card. IT is VERY pesky about them. Later, could be the wired, and If everything else did not work, just replace the module.
About the gap, It depends entirely on the software and the module. It seems that needs 20 [ms] to switch between tracks. That's the gap you heard. I have been trying to fix that, but seems impossible given the hardware. I also moved the pin from 3.3 to 5 in one of my modules ( I have 2 of them) and did not work. Put 2 diodes, as recommended and worked, but no so fine. Any other moved the pin and got fine results?