this is actually a 99 chevy Tahoe 5.7l . but should be basic info... there is a dura gold 1 year old battery in it with like 800 cc and 1000 reg. the cold start seems like is a slow crank but starts. after it warms up the crank is even harder . turns over but like pauses and doesn't seem like the power is there but still starts. connections are good . I multimeter the battery off it was normal. did it while it was running and was normal. can the alternator be messed up inside that it would do that I thought the its battery and starter. any ideas?

 

You didn't say how many miles are on your Tahoe,but it sounds like the starter to me. You already checked the simple stuff,old starters can become more prone to "heat sink",but as you have this problem cold as well,I'd pull the starter and have it tested. And if it turns up bad,you've got the core in your hand! Hint:Buy the best starter you can afford! Go cheap and you will be buying another next year! All the best!

 

I forgot to add there is a slight ignition issue with the key kinda locking up once it gets pasted the initial first turn forward its free all the way to start run etc I don't know if that is messing with anything but sounds like its separate because its changing with hot and cold starts