I have a huge miss on my `99 pickup. Nothing I do is fixing it. I have replaced plugs, plug wires, cap, rotor, distributor, fuel injectors, control module, both O2 sensors,Mass air flow, fuel pump, the brain and the miss is still there. It is really bad when cold and eases up a little after driving 10-15 miles. I am at a loss as what to do next. The engine has 236,000 miles and runs great except for the miss. The only reason for the fuel pump change is the old one went out.

 

Did you compression check it?

 

did you double/triple check the firing order and the placement of the spark plug cables?

 

Have not done a compression check. The plug wires are all correct. I don`t want to sound stupid, but what will the compression check do?

 

That will tell if you have a burnt valve, or other which will cause a miss. All cylinders should be within 5% or so of each other.

 

Found part of the problem. The new distributor cap was not any good. Put a used cap from another vehicle on and it cleared up most of the miss. It still has a slight miss left in it, but nothing like it had. Now I have a" rich " code in bank one. Anyway it is now drivable. The old truck is dented,scratched and has a ton of miles, but I would hate to get rid of it.