I'm in the same boat. You need to build muscle memory.
Get audio files of spoken English, preferably of someone with a timbre similar to yours (YouTube is a good source, download some videos and extract bits of audio with Audacity). Listen and repeat, initially pausing and repeating after each sentence, then repeating along with the audio. Pay close attention to things like connected speech patterns. After a couple of months of doing this for 30-40 minutes every day I started noticing improvements in my spoken English.
Get audio files of spoken English, preferably of someone with a timbre similar to yours (YouTube is a good source, download some videos and extract bits of audio with Audacity). Listen and repeat, initially pausing and repeating after each sentence, then repeating along with the audio. Pay close attention to things like connected speech patterns. After a couple of months of doing this for 30-40 minutes every day I started noticing improvements in my spoken English.