Chevy suburban 2002 having oil leak, sometimes it starts sometimes it wont, now rpm goes to 3 after 23 mph and whurls but no power

What is your question?

I've had this oil leak for too long, but i always add oil now weekly, it's a gasket on the bottom that i was told they have to lower the axle to fix. The starting problem i thought might be the ingention switch from the key but a mechanic told me its my starter on its last leg. Because if i hold the key sometimes it will start up, or if i keep trying it might start. It doesnt click or make any noise it does nothing when the key is in on but the lights and beeping will come on. Today, i was coming home and i noticed i wasnt going fast as traffic i looked down and mu rpm was at the 3 and my speed was at 40. I turned off the radio and rolled down the window and it was whirling like i was racing. I havent noticed the trans hitting and never had an issue like this before. When not accelerating my rpm goes down to .5 to 1 like im in idle going down hill it still had problems when i accelerated. Please hekp

How long has your 2002 Chevrolet Suburban 1500 had this problem?

Oil leak forever, starting problem 1-2 months, rpm today