The other day I was driving down the road on a long, flat section and all of a sudden my truck started missing out of the blue. Ever since it started missing it hasn't stopped. The truck is an '89 Ranger, 2.3l, 5 spd. The plugs and wires were replaced last year along with the timing belt and fuel pump. It has been running great since then until now. I thought maybe it might be a clogged fuel filter so I replaced that but it didn't help. Also, it doesn't miss all the time. It doesn't miss when its idling or if you are going down the road while it is missing and slowly release the gas pedal it reaches a point while you are letting the pedal up where it will even out. It definitely seems like it is an "under load missing" scenario. Also, the Check Engine Light is not on. Where should I start looking?

Thanks!

 

Did you buy gas recently? Perhaps you got some gas with water.

 

If your truck has a MAF, it would not hurt to check that it is clean. A dirty MAF will cause hesitation and uneven acceleration. When you feather the gas pedal to make it run smooth, you are reducing the air flow (which the MAF measures) and also reducing fuel flow requirements. You may be having an air or fuel problem, either flow, or measured flow.
Water in the gas will make the engine seem like it is herky-jerky, such that it is difficult to accelerate smoothly, or shift without jerkiness. The engine will lack power, and will want to slow down very quickly when you let off the gas to shift, thus causing jerky shifts as it is not responding normally.
tom

 

Thanks for the responses. I don't think it is the gas because it didn't start missing until I was down to 1/4 of a tank and started with a full tank on that specific fill up. Just for good measure, though, I filled it up with fresh fuel and some seafoam. I haven't drove it much since then.

The MAF is a good idea but it doesn't appear that this truck has a one.

Still looking for ideas....

 

Check the condition of the spark plugs. Make sure you are using OEM grade parts. Most ignition related issues can be resolved by using factory parts. But check the condition of the plugs now just to make sure its not an obvious issue.