Hello

I have a 2003 Ford Ranger Edge I bought new in 2003. I have always took good care of it. Has about 83,000 miles on it. Last year I put new plugs and wires in it for the first time as regular maintance. Sometimes mostly when cold it would hesitate a little then snap out of it seems like every winter or when its cold and damp out. Its summer now and warm, its hesitating again more than it ever did. Starts at like 55 to 60 and if you let off the gas it stops. Sometimes it will not at all. Put a new fuel filter in it when it started here this week really bad. Also some C foam and heat to it also. I was on a trip and bought some Amoco high Octane gas for my truck and after that it started to act up. Someone said I should have not put in the high octane and just used regular gas in my truck. Also took to a local shop and they ran a scan on it and found nothing wrong. No lights are on either. Any help would be great as I take good care of my truck. Thanks

 

Just thought maybe someone else had the same issue.

 

I've had my '03 FX4 since new also. It has also has the 4.0 engine. Mine has 118,000 and still has the original plugs, wires and fuel filter. I'm hestitant to change them out because the truck has always run great. Aside from regular oil changes and air and oil filters, I add fuel injector cleaner to the gas every 3-4 months. Perhaps adding fuel injector cleaner to serveral tanks of gas will help your truck out.

 

You may have more than one problem.

Probably a good idea to have changed the plugs, wires & fuel filter.
Did you use the specified Motorcraft plugs & wires & set the plug gap to spec & torque the plugs in, so you know the gap didn't change????

How did the old plugs read/look????

Was the station you got the premium gas from, a high volume station?????
If not, you may have gotten some premium winter vapor pressure adjusted fuel, thats causing some problems in warm temps. Or, maybe they don't pump enough premium or mid grade for the premium fuel to be fresh, or maybe it's dirty?????

Using one tank of premium isn't likely to cause problems, if the fuel is fresh & clean.

Ford cautions that long term use of premium may cause deposits & driveability problems, because our engines compression, valve & spark timing aren't optomized to use premium fuel, so over time it can form deposits & cause problems.

Have you changed the air filter & if so, are you using an OEM air filter, or an oiled cotton gauze or foam type air filter???? The two latter types are known to foul the MAF sensor if over oiled, or used in dusty conditions & cause mischief.

An acting out TPS sensor, whos resistance value is causing bad electrical output to the computer about throttle position, can cause mischief.

And of course a fuel pressure or volume problem can cause such mischief, so have you done a fuel pressure & volume over time test????

Some more thoughts for consideration.
With more clues we may be able to narrow down the trouble shoot.