1998 Discovery

Current Issue:
The car starts fine in the cold, and idles fine once started (although it does seem to idle a bit high 1500rpm or so). However, once I put the car in gear (reverse or drive) and then lightly to moderately touch the gas the car sputters and sometimes stalls like it is no longer running on all cylinders. Also while this is happening, a relay starts clicking behind the glove box. I was able to identify which relay was clicking by feeling it, and replaced it with a new one (12v yellow relay) but continued to do so after being replaced. I can reproduce the clicking by shifting from park to reverse, so it seems to be related to that somehow.

If I give it about 3/4 throttle, I can drive it when needed and once it reaches normal operating temperature it pretty much evens out and runs fine until it sits again for a while until it cools back down. The clicking relay also stops once warmed.

It smells like it is running rich when its cold, and feels like it is not running on all cylinders. I've replaced:
plugs, wires
fuel filter
fuel pump
multifunction/fuel pump relay
fuel pump harness
all the 12v/24v relays (well... 2 new cycled through the rest)

Has anyone ever run into something similar? Its strange that it starts fine, idles fine, shifts fine, but as soon as i touch the gas it craps out. It even rolls fine at idle speed without sputtering. I get the feeling that from certain RPMs (500 -1500 with the increased idle) the motor doesn't operate properly when cold, but giving it enough gas to pass that range it works fine.

I have a CanOBD2 code reader, however it gives me an error when I try to connect, so I dont currently have the OBD2 codes just yet heh.

Brief history:
Before I owned this car the fuel pump was replaced, and from time to time the fuel would cut out and I would have to unplug the fuel pump (from cargo bay, under carpet) and plug it back in. After two times doing this I noticed the fuel pump harness had a burned end on it, so I replaced the fuel pump harness with a new one (pic of burned end below). This car has some electrical problems is what I'm getting at.

 

Why don't you connect a fuel pressure guage, and see what is going on when all this mayhem is taking place? If you are still having electrical issues, the pump pressure could be really low, etc., for a variety of reasons, and you could be on your way to burning up another plug. Looking for pressure in the 32-34 PSI range, "tire" guage fitting on passenger fuel rail.

 

What brand and grade of fuel are you using?

 

Stop throwing parts at it! Have you done any poking around for obvious causes? Take out the IAC and clean the ports in the throttle body, and clean the IAC nose. Berkebile 2+2 will take the gunk right off. You should obtain a good DVOM and start checking sensors. Start with the TPS, if you lose signal anywhere in the sweep it's junk. Most TPS failures are an open circuit right off idle since that is the area that see's the most use. You will need to turn it VERY slowly to detect a fault. Check your CTS, the ETM should explain all this. You can also TRY cleaning the MAF, but if you need to drive this I don't recommend doing so unless you have another one to install. The possibility of it being junk after you clean it are high. Try unplugging the VSS and see what it does, just for grins. Rinse, and repeat.