92 Escort GT fuel issue?

I own a 92 Escort GT with a fresh rebuilt 1.8l dohc, 5 spd man.
It has been running perfect for the last 4 months, until yesterday...

If I try to drive, the engine starts to sputter when the gas pedal is past half throttle.
If I let off the gas to 1/4 pedal, it smooths out and drives fine.

I replaced the fuel filter and added injector cleaner, but still sputters...

Any ideas?

I own a 92 Escort GT with a fresh rebuilt 1.8l dohc, 5 spd man.
It has been running perfect for the last 4 months, until yesterday...

If I try to drive, the engine starts to sputter when the gas pedal is past half throttle.
If I let off the gas to 1/4 pedal, it smooths out and drives fine.

I replaced the fuel filter and added injector cleaner, but still sputters...

Any ideas?
Could be quite a few things. If it is now a consistent problem, you could have an issue with your fuel pump. If it comes and goes, it could be anything from a bad tank of gas to your knock sensor or tps sensor. Unfortunately problems like this are usually only solved by a lot of guess and testing or a trip to a mechanic.

The strange thing is now it runs perfect @ full throttle through all gears BUT...
only when its cold...
Once it reaches running temperature it loses all power and sputters like a VW bug.

The strange thing is now it runs perfect @ full throttle through all gears BUT...
only when its cold...
Once it reaches running temperature it loses all power and sputters like a VW bug.
Is it throwing a check engine light? If so, get that scanned to narrow it down. What you describe there is almost always because of either a bad O2 sensor, or the fuel pump dying.