97 Astro code po101

I have a 97 astro that has lost all power and performance. Code po101 came up so i checked for vac. leaks (none found). then replaced the MAF Still having same problem and still getting maf codes fuses all check good.Just read a post on how to check voltage and ground on the maf circut. will check all that out tomorrow. Also when the engine starts losing power and running poorly and the ses light comes on the transmission seams to be shifting up and down. don't know if that is related or not. Any help or suggestins would be greatly appreciated thanks Jeff

Check voltage at the MAF sensor and post your results. Repair the MAF problem and the transmission issue will more than likely clear up.

Voltage and ground resistance checks perfect. Signal voltage varies depending on throttle posistion 3.5-6 volts. I'm no longer getting any codes but the thing still won't run. It just falls flat on it face when you try and drive it. So i went back to the basics new plugs fuel and air filter cap rotor wires pcv valve. still the same seems like it runs much better cold as sonn as it starts to warm up it gets worse the longer and warmer it gets. pluged cat? the exhaust seems to flow fine. I tried to drive it today and it did reset one code after it was running so poorly it set a miss fire code on #3 cleared it with very little change.

Also i forgot to mention fuel pressure checks good 45-55psi

There's your problem! Fuel pressure needs to be a MINIMUM of 60psi

Fuel pump operation:
The fuel pump circuits are designed to energize the fuel pump continuously any time the key is in the START position. When the key is in the RUN position the fuel pump will operate provided the engine is running. If the engine stalls, or is not running for any reason, the ECM will shut off the fuel pump after approximately 2 to 3 seconds.

Fuel pressure test:
Install fuel pressure gauge to the test port near the distributor. Turn the key to the RUN position, (do not start the engine). While the fuel pump is running, fuel pressure must be 60-66psi. After approximately 2 to 3 seconds, the fuel pump will shut off. Fuel pressure must remain between 55-60psi for several minutes. A drop in pressure below 55psi indicates a leak. Most likely the fuel pressure regulator or the lines under the upper intake manifold.