hello everyone this is my first post on this forum even though i have used its information many times, but i have finally come across a problem i cant resolve.

1990 S10 Blazer
4.3 vortec
700-R4 Tranny

New Parts:
New fuel tank/pump/soft lines/sending unit/filter
Radiator/thermostat/housing gasket
battery, grounds, positive cables
IAC, its pigtail (soldered)
Water Temp sensor
New plugs, wires, cap, rotor, coil, and ICM
K&N air filter
Cat deleted, straight to single in dual out flowmaster
4" drop block rear, 2" drop spindles front
8000K HID's
New MAP sensor
EGR was blocked off, but i cleaned it and put it back on
All vacuum lines replaced, all hoses replaced
EVAP canister deleted
02 sensor replaced
Tranny Oil flushed, filter and gasket replaced
Timing adjusted to factory 0degrees at BDC

My problem is that when i first start the truck it idles beautiful, drives out of the driveway powerfully while shifting smoothly and in less than a mile of 50mph driving (after warming) the motor becomes very lethargic. Attempting to accelerate too hard causes a POP in the intake..miss, backfire, hiccup whichever it may be called, but def. in the intake.

You see all i have replaced and i have run out of logical answers to its problems, i have given you all i have done to possibly help diagnosis.


I have included youtube videos to help!:


First starting truck while engine is cold, you can see it running out of the drive way fine and accelerating to highway speed fine, then a little further down the road i release the accelerator and pile into it again and the motor goes POP...POP...VROOMMMM, very consistantly while being lethargic

YouTube - ‪90 4.3 blazer problem‬‏


Second i turn around and head back home the first acceleration is WOT....you see how weak it is acting????

YouTube - ‪90 4.3 blazer‬‏


Lastly returning to its sleeping place i idle and rev the truck so you can see the small amount of surge once its warm.

YouTube - ‪1990 4.3 blazer problem‬‏



Please any help in its diagnosis would be greatly appreciated....if i cant fix it im gonna park it in the bayou across the road and get a toyota

 

do you have a cat converter on this truck?

 

Its listed in the things that have been done to the truck, the cat has been deleted, just the Y to a single out to a flowmaster

 

ok when you did the tune up wires cap rotor plugs did you use ac delco parts .

these engines crave for ac delco and wouldnt run great with any other markets out there

 

the plugs were AC delco, but the Wires, cap, rotor, ICM, coil were all BWD performance.
The problem existed before these replacements and was not affected by them

 

you never know but she idles ok right?\

when my truck had that problem i had a clogged cat i replaced every thing to ac delco and i needed to replace my fuel injection spider then she ran great since . the cat backed up so much crap into my spider

 

Yep, the idle is very reliable, but if you look in my third video after it is warm the motor surges in rpm JUST a little (evident by the oil PSI gauge since i dont have a tach yet)

 

yea thats why i thought it was a miss fire

i dont remember checking if you had an engine light on

 

No, no miss that i can tell, the motor is smooth as glass, just bumps rpm about 100 or 200 when warm

 

there should be a vacuum line behind the intake is that leaking?