I have a 2000 Chevy blazer that sat for 10 years and I bought it in hopes of getting it running and dailying it, I have replaced,

fuel tank
fuel pump
fuel filter
spark plugs
plug wires
distributer (the entire thing so rotor and cap as well)
ignition coil
throttle position sensor
ignition control module

yet I am still having a misfire, when it first starts it’s decent, not perfect, when I press the gas it couldn’t pull it’s self out of a paper sack. After about a minute I can hear the engine stop misfiring as bad and I’m able to press the gas and go again. I took it to s and s tire to have a diagnostic done on it and they said the ignition control module, ignition coil and distributor was bad, so I replaced them myself and still having the same issue, almost worse then before; before it was just a rough idle and now when I press the gas it doesn’t want to move at first. Please help

 

There are members here who definitely are better at diagnosing issues such as these, but let me give it a bump and offer some basics that might help.

First off, you might want to get a proper diagnostic tool for yourself that can give live data readings. I know I've seen this advice given before. This will then provide the OBD codes that can help guide the diagnosis.

Did you replace the fuel lines or at least flush them? Have you checked if the fuel pump is working correctly by providing enough fuel pressure to the engine?

You didn't replace the fuel injectors. Those are hard to find. Perhaps there is a problem with them or the fuel pressure regulator for them?

Have you checked the spark plug cables? One way to check is a visual inspection to see if they are cracked or have had critters chewing on them. If the insulation is bad, the electricity in the wires can arc to the engine instead of across the spark plug gap. Another way to check for this is to idle the engine while watching the engine in the dark. You'll have to take out the under-hood lamp bulb and find a dark place. Look for sparks. Sometimes you can hear the spark from the wire. This is how I learned my spark-plug wires in my old Dodge Dart were bad and causing a misfire. Be sure to raise the engine speed too as sometimes the arcing might not occur at idle when the pressures in the cylinder are no so great to prevent arcing at the spark plug.

Was the replacement distributor a GM/AC Delco part? From what I've learned on the forum, using non-GM parts for the cap and rotor can cause issues such as misfires.

Hope this helps.

 

Old vehicle. 24 years old. When youve guessed and replaced all the parts, suspect bad wiring.

MUST start by verifying 14 volts or so at the ignition module and coil. Severe misfire results from bad wiring connectors or a bad ignition switch.

The place to start is an oscilloscope on the coil primary PLUS to verify that the voltage is not dropping when the module turns it on. Honda Goldwings had a severe problem with this in the late 80s , 6 volts on the coil + when the module turned on. 60 some bad electrical connections caused weak spark, charging failure and engine overheating.

Other test, make a 3 foot long jumper wire with a 5 amp fuse, temporarily connect it between the battery + and the charging system feed to the distributor and coil. See if the misfire goes away.

On my 95, I made a wire harness mod to put a fuse and relay under hood to bypass the coil power around the ignition switch and old wiring. The relay is triggered by the original power feed to the distributor, the relay closes and ties the charging system to the coil and distributor.

Be careful that the jumper wire must be disconnected before turning the engine off else the jumper will provide current around the ignition switch and the engine may not shut off with the key.

This is the same mod as for " dim headlights" and both should be done for 20 year old vehicles.

Misfire should show up as black or brown spark plug tips.

 

It could be as simple as the plug wires being installed incorrectly. Number 1 and Number 3 wires are easy to mix up.