Poor Preformance, stumbling issue

[Gramps]

Hey guys, need some help figuring this out.
First off its a 95 reg cab k1500 5.7 tbi.
It starts and idles fine, under very light throttle its ok, but the shifts (shift points) seem delayed (they are firm, noslippage) Under anything more than light throttle it stutters, and when it does go it does not have the power it should. I knowits. It a not a racecar but damn its like a 4cyl in there lol. I did verify its a 5.7 not a 305.

Full tuneup done(cap rotor plugs wires air filter). - no change

Data streamed it- coolant temp working, tps working, map sensor reading high, o2 says its leaning way out when you hit the throttle.

Had spare (known to be good) map so I swapped them. -no change

Any thoughts??

 

[93blackthunder]

coil?

 

[Horns]

Check check check BEFORE you throw money at a full tune up.

If its leaning out, check the fuel! Hook up a fuel pressure gauge. The pump may be going out. If your pressure is fine, check and see what the spray from the injectors look like.

-Via Mobile-

 

[DGA1]

Have you changed the fuel filter recently?

 

[Gramps]

Well I did the tuneup because it was needed. Wires were still gm originals LOL!

Looking down the tb, the spray pattern from the injectors looks even between the 2, and strong. I know a pressure check is next, but have to hunt down a tbi pressure adapter.

As for the coil - I've never seen one cause the engine to lean out as you increase the throttle.

 

[93blackthunder]

Well i just had a coil go out and it was doing the exact same thing

 

[Gramps]

Not the coil, swapped it with another and no change.

About to start pulling out hair haha...

 

[VorTecxas]

Timing! I keep seeing you TBI fellas with this same problem. Check your timing. Those distributors are not the most reliable, even new ones won't keep consistent time. Be sure to unhook your advance wire under the passenger side of the dash.

 

[TylerZ281500]

all my firends and my TBIs were either silent killer fuel pumps that went out with no warning or timing going berserk. i would try advancing and retarding distributor for s and giggles, and check your fuel pressure.