3rd cylendar issue?

[96GST16g]

the first time i blew my motor it would only hold 30% of air capasity in the 3rd cylendar and the secound time i spun a bearing on the 3rd cylendar could this be linked to a certain issue or may be a shitty build? running a 16g 3 inch turbo back exhaust and no tuner stock boost and it blew after 100 miles of rebuild secound time first time had 169k on original motor as far as i know