Has anyone run into a problem we’re after the engine it tuned up there is a misfire at about 35 mph? They put in new plugs and wires cap and rotor.. they New have put in one more spark plug and has said it might be the fuel system now... bad cap or rotor??

 

Nothing like paying someone to tune up your truck then having to rely on someone else to fix it for them.

 

Check plug wire routing, and firing order.....

 

How was it running prior to the tune-up?

Did they replace the plugs with the same brand that were removed? Is it possible that they cracked one or more of the plugs during installation?

 

it was running, fine.. they put in the same brand plugs new wires cap and rotor... they also replace the #7 spark plug again.. they said when it happens again they are going to replace the fuel injector. this seems like a scam. but the truck will miss fire at 35 mph . if you step on it or go slower it seems to run ok.

 

After checking the wire routing then you should check the resistance of the wires, there might be a manufacturing defect in one of them. They should read 250-1000 ohms per inch.