Usually in the mornings when I start up my 92 s10 blazer with the 4.3L, it surges and feels like it’s gonna die until I constantly give it gas. Today the service engine light went on but turned off once it stopped running roughly and warmed up. It only does it when the engine hasn’t been warmed up. The previous owner put a new cap, rotor, wires and a distributor coil. The fuel pump is new and idk what else it could be. The plugs are really old, so maybe the plugs are making it run badly? If anyone has any ideas help me please!

 

I wouldn't think it's the plugs if runs normally once warmed up. Although if they are old, then a fresh set certainly wouldn't hurt.

Can you check to see what codes are stored? Even if the light went out, it may have stored a code that will help you diagnose.

I believe I've read about bad TPS sensors causing similar issues, so you could check that with a multimeter. Otherwise possibly IAC valve, Small Vacuum leak, or stuck EGR valve, but I'd start with trying to pull the code. Pretty easy with the paperclip method.

 

Do these have a air temperature sensor?

 

The 92 most probably is a TBI injection, but we have to make sure which injection is on your Blazer.
Is it a TBI or a CMFI injection? TBI is carb style, CMFI has round manifold tubes.
TPS cannot be ruled out.

As soon as you crack the accelerator by a little bit, the engine stabilizes?

Some cheap preliminary checks to rule out other issues:

- TPS for correct seating, no looseness, wiring for damage.
- Vacuum leaks - check all the hoses connected to the manifold for rupture, cracks, crumbling apart (notorious for the mid 90's models)
- Ignition timing - needs control wire to be disconnected and timing light.

 

@ christine

The TBI models do not have an IAT sensor, while the CMFI do.

 

Yes it is a TBI engine by the way