late shifting from take off??

[turbo john FL]

ok i am posting and running to work . so thanks in advance for all help here. my car is shifting ok some times but other times and it is getting more often ! it will not up shift. unless ilet off the gas and re gas it to make it shift i tried to see how far it would go before shifting up in low gear from a roll off and it got up to 4000 rpm before it shifted any ideas at what i should look at wouls be great also it is not slipping or anything
thanks john

 

[77 cruiser]

I'd pull the pan & see if you have any debris in it, you could have something going away. Never hurts to check

Jim