T2 trans doesnt like to shift into 4th from top of 3rd
 

Feels like the transmission is just saying nope haha, can do all other gears until 4th, from top of 3rd 6800-7200ish under power it will how ever shift no problem just cruising, just getting up to speed, no hesitation will plop into gear no grinding no issues, its only under power it doesnt like to shift, any ideas? running redline MT90 GL4 oil, fresh from last year with under 4000kms on it! let me know!