Hello everyone, I have this problem with my 99 2.5l 5spd ranger that when I start it, it runs smooth but if I rev it up it dies immediately. When going to restart it, it skips and sounds as if there is loss of compression but eventually starts and runs rough until it smooths out after about 30 seconds. Am getting a p0302 pending code and while driving i can feel the misfire and acceleration is bogged. Idle seems rough also at a dead stop. Any help would be greatly appreciated as I have had this ongoing issue for 2.5 years!

Things replaced are:
Maf, spark plugs and wires, coil packs

 

I've got a 98 2.5l manual trans doing something very similar and have been fighting this beast for a while now, it runs extreamly rich, has misfire on cylenders 3 and pending on cylinder 1, it's a new motor I can't seem to figure it out, did you get yours figured out?

 

Hi Faze,
While your problem could be a number of things, it sounds like it could possibly be a fuel delivery issue. Or possibly an IAC (Idle Air Control) valve issue.
Some things to consider regarding fuel delivery-

Clogged Fuel Filter- If your inline fuel filter( usually somewhere on the driver side frame rail ) hasn't been changed in a long time it could be clogged thereby starving the engine of fuel. Also cheap aftermarket filters can be a problem out of the box and can potentially ruin an otherwise good fuel pump.

Dirty or malfunctioning Fuel Injectors- Dirty fuel injectors can provide sporadic fuel delivery, or none at all depending on how dirty/clogged they are. Or there could be a wiring issue.

Bad fuel Pump- There are several factors that can cause a fuel pump to go bad. Sometimes the sock ( a filter on the end of the pump assembly ) can become clogged or even fall or rot off and lay in the tank. Or if the vehicle is commonly ran on a low or empty tank the pump overheats since the fuel actually keeps the pump cool. I prefer to keep my tank full and never let it go below a 1/2 tank.
It's also been said that a vehicle gets slightly better gas mileage on a full tank although I don't know if that's been proven wrong as of late. If nothing else, it's better to fill a tank from 1/2 full to full than it is to fill an empty tank to 1/2 full all the time. Sometimes there could be a wiring or ground issue causing intermittent or full pump failure. A loose ground wire can cause the pump to work or not work as it bounces around making then breaking contact. Even the wiring to the fuel pump inside the tank can become corroded or loose/disconnected.

If you have or have access to a fuel pressure tester you might want to test for fuel pressure with the engine off and the key in the Run position to check initial pump pressure for 2 seconds each time the pump is turned on and then during startup and at idle.
There are several good videos available showing the process.

For the IAC:
There are several threads in this forum going into detail on the function and issues of the IAC valve.
Ron D has posted a lot of good information in most of them. Just search the forum for "IAC Valve".
I would post some but I'm running late. I just wanted to post some possible things to look for off the top of my head to get you going.
Of course this only for the fuel side of proper engine operation. There could also be a a compression or spark issue.
I hope you get it figured out.