So here's my issue my 88 iroc z28 automatic is stuttering and not advancing past 4000 rpm in drive or overdrive with full throttle however first and second Wil both run up to 7000 with ease any thoughts I have switched from tpi to a 600 Holley with vacuum secondary I'm very confused by this

 

Make sure you're not running out of fuel or developing a hard misfire.

 

Hard misfire?

 

When you downgraded to a carb did you replace the factory distributor? What did you do to reduce fuel pressure?

 

added a Holley Blue with a regulator set it at 5lbs

 

Is that a dead head or return style?

Also did you replace the distributor?

 

dead head and yes hei distributor

 

also should mention this issue just started this week has been running fine for months every now and then I noticed a stuttering at 4000rpm in drive but the it would proceed now it's like hitting a wall every time but only in 3rd and 4th gear no issues at all in 1st and 2nd could it be the vacuum secondary malfunctioning? Also I noticed a small spot on 1 plug wire where it had bumped up beside the header

 

IF you are only having the problem in first and second gear then the problem points towards a trans issue.

 

no it's only happens in drive and overdrive NOT 1st or second

 

Could be the HEI module going south. They tend to act weird right before they die completely. Or, the full-time 12v power wire going to the HEI. If the voltage isn't the full 12v, goofy things can happen.

 

Hard misfire is when a plug stops firing, you get crossfire in the cap, or a mechanical problems kills a cylinder.

 

Move your fuel pressure up .5 psi a time and see if that helps. Sounds like you are running out of gas. I had a similar issue with my car when I got it. The POS did a V8 swap and had the fuel lines routed wrong with the return line before the regulator. Fuel pressure wouldn't stay high. Put in a AFPR with a return on it, and haven't had that issue. However, I though Holleys needed 6-7.5 psi. Not sure though as I haven't had a Holley.

 

Is his torque converter locked while in D and OD?

 

Is the factory in-tank pump still operating? If not, did you remove it from the tank?

 

problem solved!!! Turned fuel pressure up to 7.3 psi at idle and it runs great

 

Problem band-aided. 5 psi is plenty for a Holley, 7 is max (so you don't overwhelm the needle/seat). Carbs don't operate on fuel pressure, they operate on fuel supply. Pressure only insures the fuel can overcome acceleration and keep fuel flowing up to the floats.

You didn't answer my question. So I repeat: Is the factory in-tank pump still operating? If not, did you remove it from the tank?