How do I send tweets with flame sensor and ESP8266?
I guess your baud rate and network connection with the wifi module is working fine. Have to say that it is a bit difficult to get the data sent to ThingSpeak with ESP8266. I actually did some experiments to get the data sent. The problem is actually with the delay. Adding a delay of 5000 ms between sending the tweet length and the tweet content sorts it out. You can use GET format. Check out this Instructable.