big problem need help!! please help

i have a 1997 s10 4.3 vin x. it has started misfiring badly, its a 5 speed and i barely have enough power to get off the clutch. i have 2 put it all the way to the floor for the rpms to rise, when i shift out of second into third gear i cant keep speed i drop speed and have to downshift. no power to go up hills. i need help. anyone know what could be the problem? p.s. the ses light has not came on, no codes at all. i have done a tune up on it and hasnt helped, changed fuel pump and hasnt helped. it shakes horribly and barely runs. any help will be greately appreciated thanks.

How is the fuel pressure and fuel filter?
Any flashing check engine lights?

Got good hot blue spark to all spark plugs?
Have you checked cap and rotor?
What kind/brand of spark plugs and fuel pump?
The only true test on a fuel pump is to check the direct fuel pressure from fuel pump.
A quick test is to block off the return line and see if fuel pressure comes up to 75-85 lbs.
But do not run the pump at full pressure very long.
Also when testing fuel pump and pressure you need to tape a gauge to outside windshield or outside mirror and drive it on the road for 20 -30 minutes
until the pump gets has run a while to check for a pump fading out after hot.

Hard to start cold or hot and fuel pressure testing guide lines.
Check cold start fuel pressure.
Check engine running fuel pressure.
Check engine running on the road fuel pressure.
Then shut it off and watch for fast leak down.
Pinch off at rubber part or block off return line and check full pressure.
If pump has full pressure with return line blocked and low pressure without it blocked most usually the fuel pressure regulator is leaking or not holding pressure.
Later V6 and V8 gm engines should have 60-66 fuel pressure.
Cold start should be 64-65 lbs of pressure.
If you do not have full fuel pressure on a cold start the injectors will not squirt fuel.
Do not leave home without it.
Engine running should be 60-66 lbs pressure depending on engine load.
Full pressure with return pinched off should be 75-85 or more.
And if it has a fast leak down after shut off you have a leak in system.
Post back fuel pressure readings.

i have to get a fuel pressure gauge, but i have checked distributor and cap and rotor and its all good changing fuel filter today, when i was getting it inspected they said something about the engine computer was going bad but that dosent make sense, i pulled the egr valve and it was filled with carbon everywhere i cleaned it best i could and drove it and maybe gave me 2-3 more horsepower(barely enough to tell)

Parts places sell /loan /rent fuel pressure gauges.
Get one and post back pressure radings.

A cloged not/working egr gives more HP than one working good.