95 suburban....she has bad mood swings

I need some help and idea on how to fix this suburban. Its a 95 with the 5.7 non-vortec. I bought it with a blown motor and got a new 5.7 from a friend. The new one ran great when he pulled it out of a 89 suburban. Everyone I talked to said it was the same block, just different electric components. So I put all the 95 components on the 89 block. Okay here is what she does, sometimes. I will give it gas from a dead stop, like normal, not hard or anything, and it will shift fine into 2nd, and 3rd. But sometimes it acts like its not getting enough gas and the power will go away. I can give it more in the pedal, and it will take off alright, or make it worse. Also it does in all the gears, depending on her mood. She also will die at stop signs, and if its at an idle for awhile. Another thing I don't understand is she also running rich, black smoke out the tail pipe at hard acclerations. I hope I make sense, if you can help I will greatly apperciated.

Here is what I have replaced so far: Cap, rotor, plugs, wires, fuel filter and pump, intake manifold gasket, throttle body to intake gasket, vaccum lines, egr valve, egr solenoid valve, and throttle positioning senser. I have also checked all fuses.

I need some help and idea on how to fix this suburban. Its a 95 with the 5.7 non-vortec. I bought it with a blown motor and got a new 5.7 from a friend. The new one ran great when he pulled it out of a 89 suburban. Everyone I talked to said it was the same block, just different electric components. So I put all the 95 components on the 89 block. Okay here is what she does, sometimes. I will give it gas from a dead stop, like normal, not hard or anything, and it will shift fine into 2nd, and 3rd. But sometimes it acts like its not getting enough gas and the power will go away. I can give it more in the pedal, and it will take off alright, or make it worse. Also it does in all the gears, depending on her mood. She also will die at stop signs, and if its at an idle for awhile. Another thing I don't understand is she also running rich, black smoke out the tail pipe at hard acclerations. I hope I make sense, if you can help I will greatly apperciated.

Here is what I have replaced so far: Cap, rotor, plugs, wires, fuel filter and pump, intake manifold gasket, throttle body to intake gasket, vaccum lines, egr valve, egr solenoid valve, and throttle positioning senser. I have also checked all fuses.

Need to be put on a good engine capable scanner and checked out for rich running.
Watch engine tempt sensors real close.
Check all engine running sensors for proper operation.
Post back and engine codes to.
Also check out fuel pressure and puel pumo for proper operation.

Thank you for the help. I finally got a scanner that would read the codes. It said the O2 sensor was running rich, and lean. Thought it couldn't do that at the same time, so I replaced it. She runs great now. So if anyone has these problems I hope this helps.

Thank you for the help. I finally got a scanner that would read the codes. It said the O2 sensor was running rich, and lean. Thought it couldn't do that at the same time, so I replaced it. She runs great now. So if anyone has these problems I hope this helps.

You are welcome.
02 sensors swing from lean to rich all of the time.
But should not holds lean or rich.
What was the code no or no's?

I can't remember the codes exactly, but I remember the definitions.

1. O2 sensor malfunction
2. Map signal voltage high
3. O2 running lean
4. O2 running rich

These all pulled up when I scanned it. After I replaced the O2 and cleared the codes, I re-scanned it. There has not been any codes since then. She runs like a champ.

I can't remember the codes exactly, but I remember the definitions.

1. O2 sensor malfunction
2. Map signal voltage high
3. O2 running lean
4. O2 running rich

These all pulled up when I scanned it. After I replaced the O2 and cleared the codes, I re-scanned it. There has not been any codes since then. She runs like a champ.

Sounds like a good fix.
Good luck

Hello, new here and to the truck...a 90 2500, did and engine swap, having issues as described, mufflers will be replaced this week, big hole in the sensor side, also oil pressure gauge is erratic, no overheating, or smoking so im thinking its the gauge or wiring, while idleing the gauge will go to normal just before it stalls

Hello, new here and to the truck...a 90 2500, did and engine swap, having issues as described, mufflers will be replaced this week, big hole in the sensor side, also oil pressure gauge is erratic, no overheating, or smoking so im thinking its the gauge or wiring, while idleing the gauge will go to normal just before it stalls

Welcome to AF on yoyur first post.

It is best to look for and hit the New Threwd button and start a new post on your truck and problem.
Give all repair done info and problems.
What all was done on engine swap?
what engine and did younstay with same size engine?

On oil pressure problems it is best to put a manual test gauge on it and read the real oil pressure.