Hello @anon1673955
I believe the issue could be in the loop() frequency. Since it's close to 20ms (coming from the delay() ), it means that it will definitely be exceeding the 4 requests/second limit for paid accounts at Ubidots, or the 1 request/second limit for STEM accounts at Ubidots.
I'd recommend you maybe use the esp8266 as data logger and then send the data to Ubidots, however, this might not be the best approach for your project as applications such as EGC monitoring require an infrastructure for very high frequency data and Ubidots wasn't built with that sort of applications in mind.
I'm curious to know if the loop had the same delay for when you sent only one variable, because this should have rendered the same result as if sending the 3 variables.
Best regards,
Sebastián