I have recently recieve my brothers broncO. It's a 88 automatic wIth overdrive and is a 5.0 liter. It use to run goOd but has set for a few years and now I'm trying to fix it. It fires in all cylinders for like 5 seconds then starts missing. So I changed all the spark plugs, wires, distributor cap, and the button. Basically a tune up. I'm 17 and not really sure of what else To do because it still fires up great and then misses. You can drive it still but its just so rough I dont know what to do. Does anyone have any ideas or have had this hAppen to them.

After it fires up only 3 cylinders work good. 5 of them dont.

 

I would change the fuel filter for starters. Very easy to do on a 1988, just break the plastic U shaped clips off and work them out. The new U shaped clips will come with the new filter.

 

id also run some fuel treatment into it could be gummy injectors. when u first turn it on the fuel pump primes n gives extra fuel but when it goes away if its gummed up it can cause a dead cylender

 

Could it be the throttle body sensor

 

If it has sat for a few years, I would suspect the gas in the tank to be all varnished up. Does it smell like turpentine if you take the gas cap off and push that center button and smell in there? If so you may have to take the tank off and flush it out somehow. At any rate I would start by changing the fuel filter. Also make sure you have plenty of fresh gas in there if you don't have to flush the tank.

 

After you change the fuel filter just get a couple of gallons(not cheap) of turbo blue or some type of race fuel and add that to the tank. Should help raise the octane.

 

are u talkin about the throttle position sensor or iac valve they are the only 2 on the throttle body