Engine will not go over 4000 rpms when under a load

IF you have a carby then take it apart and clean it out as all the throats are not working properly including the accelerator pump.

I wouldn't run it till the freon level was checked; if it's low, you could damage the compressor.

Hello.

The following are the general instructions on the start of diagnosing any electronically controlled engine or transmission problem.

The engine and the automatic transmission (transmission control is only for automatics, engine is still computer controlled no matter the transmission type) in this vehicle are computer controlled and in most cases when a fault occurs a fault code is stored in the memory of the computer control module. There are exception to this, such as the Mass Airflow Meter and fuel pressure problems. What must be done is to have all the basic testing done such as a scan of the system for fault codes as well as a check with a live data scanner tool for engine functions that are not within range of normal, a trained technician is required to know what is correct and what isn't, then based on careful diagnostics done from a factory repair manual the correct part is replaced or the wiring repaired or the computer replaced (known as the PCM), which is very rarely the problem. Other basic checks must be done as well such as mechanical problems with the engine as well as engine state of tune and mileage on the engine. The transmission can have mechanical issues as well such as no gear engagement at all or a failed pump or other pressure related problems. Also engine mechanical problems ca cause many drive-ability related problem such as rough idle and other symptoms

crank sensor failing, still reading signal but sporadically. can also help if you replace cam and crank sensors at same time.

At 4000 rpm what does your speedo say. Your computer may be limiting both your mph and your rpms. I have a 2004 Ford Ranger at 90 mph the engine sputters and seems to miss. It will stay at 90. In neutral it revs fine. My problem is because of chip programming in the computer. Your problem may be the same.

cutting out and sputtering at 4000 rpms are normal, its the rev limiter kicking in, all of them do it, as far as hard starting, is it just sense its been cold?? might want to put some fuel stabilizer in it.

C-4, C-4, C-4

This model car has a "permanent" Fuel filter/pump combination. It is not meant to be changed. The filter/pump combo is in the fuel tank and can be accessed from under the back seat. I am highly doubtful that the filter is the malfunction you are experiencing. When your vehicle has low power and runs rough rough at low RPM's and then starts misfiring at 3500 RPM, it sounds like your timing belt has stripped some cogs and is in the process of shredding. THIS IS AN ENGINE EMERGENCY!!! IF THE BELT FAILS COMPLETELY AT HIGH RPM IT WILL DESTROY YOUR ENGINE!!! Do not fool around with changing sensors until you have had this checked out. If your DTC is saying that the MAP (Manifold Absolute Pressure) sensor or TDC (Top Dead Center) sensor is bad, check the timing belt.

Check all vacuum sources for a leak. I wouldn't race engine over 3000 without a load on it.

mine sputters under 4000rpm