Just recently bought at 99 SS it’s got a bad transmission supposedly. But I’ve got a feeling it could be bad but maybe not. It sometimes goes into gear and moves and I can go through all the gears and it moves. Then idk if it slips or what. But it won’t move just revs. Could it be a pump issue or clogged filters? Just wanting to see what someone who know’s transmissions think. It’s a 4L65E.

 

Does the Automatic Transmission operate when the Engine/ Transmission are COLD...
But stop operating once the Engine/ Transmission has WARMed-up to operating Temperature?

 

yes soon as you start it it will move it can run like 5 min and then I try it does nothing. Just rev

 

Have you checked the fluid? Is the fluid burnt? Sounds like a fried transmission to me. Drop the pan, I bet you'll find most of your clutches lying in the bottom.

 

You will have to start out by purchasing an Automatic Transmission Line-Pressure Gauge (Reading 0 to 300 Psi).

One of the Automatic Transmission Forum Moderators (MRVEDIT) recently posted about an inexpensive Line-Pressure Gauge.
He said it was on Amazon.com, Item= AT5550... Costing about $35.

The Line-Pressure Port is on the Drivers side of the Transmission Case.
It is rear of the Bell-housing; and above the shift-linkage.
There is a small Plug threaded into the Line-Pressure Port......
Shown in the image below:

 

for sure smells burnt

 

is that to see the pressure of the pump?

 

No, it is the "line" pressure which can be changed by the Pressure Control Solenoid. So it might be around 60 psi at idle, but 200+ at WOT.
We are suspecting very low pressure, which could be due to low fluid level, clogged filter, worn pump or leaking hydraulic circuits.
Besides measuring the pressure at idle, it is very useful to measure it in Reverse (foot on the brake) because the hydraulics boost this to near full pressure.
Even with the car in Park or Neutral, blipping the throttle should show big jumps in pressure.

The AT-5550 pressure gauge comes with the fitting to connect to the trans and a 6 ft hose so that you can e.g. hold the gauge to your windshield under a wiper blade to monitor it while driving. Just keep the hose away from exhaust pipes.

From your symptoms, we expect the pressure to start OK, but drop as it warms up. But it is good to know for sure instead of just guessing.