1st thru 3rd are fine but when i go to 4th it pulls but there are some slipping i think...please advise

 

My f3 did it and now my 954 starting to do it on no clutch shifting. Just a clutch going bad. pull in the clutch just a little when you shift and it shouldn't be a problem. Or get a new clutch, I recommend a clutch with a kevlar plate

 

Check your clutch. Mine went out last year, i first started to notice 4th gear was slipping. After removal of the unit to check it and measure the plates turns out i had a couple of cracked plates.