NEED HELP slow cranking

[Nrbort]

I have a 2001 seafood gts and it’s cranking very slowly and won’t spin any faster unless you take the plugs out
Yes it has a good battery jump pack and truck
Yes the start is fine replaced it twice
Essentially it turns stops then turns and stops
And yes it has perfect compression

 

[ram_says]

Pump not locked up?

 

[mikidymac]

Never ever use a jump pack or jump from a running vehicle with these.
Pull the sparkplugs and make sure you can turn the driveshaft a full revolution easily by hand.