99 blazer hesitation/stalling issues

I have a 99 blazer with some issues that just can't seem to figure out. I have had the trans rebuilt, new intake, manifold, exhaust, spark plugs, and among other things just replaced on it.

When i go to start it up it seems fine, untill i either put it in reverse or drive, and go to gas it it seems to hesitate. Sometimes but not all the time, i can put it in reverse and just gluide out of a parking space it hasitates and then stalls out.

i have had my brother look at it and had a computer hooked up to it. These are the codes that have came up, P0171B1 P0174B2, P1441B, P1380c

There is no engine light on, when i start it up thats when i have the problem of hasitation or stalling, i usually leave it in park and reve up the engine a bit tell it stops. Still going down the road i will still have the same problems.....

Any advice?????

How's your fuel pressure?

Are your getting a good spark?

Here's some help with your codes
http://www.obd-codes.com/trouble_codes/

Start with fuel pressure tests, like Ralph said. Static and dynamic tests.

Do you have a fuel pressure gauge?

Does the engine lope idle when warm? Up and down rpm's?

Key on, engine off, fuel pump running: Pressure must be 60psi to 66psi and must remain above 55psi for 3 to 5 minutes after the pump shuts off.

Have you checked out your cat. converter? I just did my transmission a couple weeks ago. While I had it off we checked the catalytic converter and it was trashed. My 99 Blazer threw misfire codes every once and awhile. We fixed the catalytic converter, and I feel like I got 100 h.p. back. No codes have come up. Just a thought.....

TWO WORDS.... TEMPERATURE SENSOR.... will cause the most problems and exactly those. especiall since you just had intake off. I did the same thing.

Always start with the first DTC that is retrieved, (any DTC's that are retrieved after it can be caused by the first one). Diagnose and repair it, clear the memory, complete a drive cycle and see if any DTC's pop up. The first 2 DTC's are both lean codes. The ECT, (Engine Coolant Temperature), if disconnected, or is faulty, will set a DTC indicating a problem in the ECT circuit, and a DTC indicating the engine is running rich, not lean.