Please help! Have checked fuel pressure ok at all stages.
Removed cat. converter to ensure it isnt plugged.
Replaced cap rotor and plugs (AcDelco)
Cleaned MaF also unplugged MaF no change in running.
Checked for accessive play in rotor seems normal.
Any insight greatly appreciated and TY in advance!

4Dr. 4x4 4.3

 

Have you checked the fuel filter for restriction?
Does the check engine light come on with the bulb check, and then turn off?
Does the check engine light come on or flash while driving?
Are there any codes in memory?
What were the fuel pressure and leakdown readings?
Did you put silicone dielectric grease on the terminals inside and out of the cap?
How old, and how many miles are on the plug wires?
Does the transmission shift normally?

 

Have you checked the fuel filter for restriction? New filter
Does the check engine light come on with the bulb check, and then turn off? yes
Does the check engine light come on or flash while driving? Comes on doesnt flash
Are there any codes in memory? Lean code dont know exact code GF took it >.<
What were the fuel pressure and leakdown readings? 62 psi went to 55 and held at leak down test
Did you put silicone dielectric grease on the terminals inside and out of the cap? Yes
How old, and how many miles are on the plug wires? I havent replaced them but look fairly new no arcing noticed on a soak test.
Does the transmission shift normally? When it is acting up doesnt seem to want to down shift.

Apologies for not giving more info at the time.

If I do a capacitive discharge it seems to run pretty well for a short time then will go bad again.

 

Good job with supplying info

Lean code: Without the exact DTC, a lazy or dead oxygen sensor would just be a guess, and your 97 has 4 of them... mighty expensive guess

Another possibility could be the ignition switch. The switch used on 1997 is unique to that year and it's known to cause several different intermittent electrical issues, including transmission shifting problems. It can set seemingly non-related eroneous DTC's in memory. This thread explains: https://blazerforum.com/forum/articl...-switch-33465/