The leak on the passenger side is from the heater core under the dash. It is a common problem. Everet posted a how-to on replacing the core without having to pull the dash. The core will need to be replaced. I don't think any stop-leak product will fix it. You can check Rock Auto (online) for prices. Sometimes they have closeout parts that are a killer deal. If you can't get a new core anytime soon, you can always bypass the core with a heater hose running from the engine's flow-in to the flow-out. It's still warm in TX. You've got a few months before a heater will be desirable... I think. eek

Your ECU is on the floor board where the radiator fluid is collecting. That could be the reason for your poor performance - a wet computer. I suspect you have other problems that are more likely to be the culprit. But a wet ECU does not a happy Sporty make...

I had the P0171 code many a time. It has always been associated with a leak in the throttle body assembly between the intake manifold and the MAF. I recommend checking the rubber flex hose from the MAF housing to the metal intake tube. Look in the deep parts of the corrugations. I found gaping holes in mine caused by dry rot. I also had an issue with the gasket between the butterfly assembly and the metal tube... and the intake manifold (upper portion). I learned to keep a roll of the gray gasket material on hand so I can cut out a new gasket when needed. It's not hard to do and is much cheaper than buying the gasket alone... and not getting the right one.

An air leak as described above will kick the "system lean" code and can cause the "misfires", poor acceleration and rough idling. It's making the ECU think the fuel-air mix is off, which it tries to correct. This is all based on the downstream values generated by the O2 sensors (post burn exhaust). But because the leak is after the MAF sensor, the ECU doesn't know its extra air coming in because it's using the MAF value to estimate the air volume. The ECU is great when nothing is out of whack. But it's ability to "correct" for out-of-norm values is super-retarded, to say the least. With random misfires on all cylinders, an air leak in the intake is a prime suspect. I recommend starting there. I'm strongly suspecting the corrugated hose...

You should also pull back the carpet on the passenger floor board and see if the ECU is getting soaked or soggy. FYI - do not ever work on the ECU or hot wires with the battery connected. I did this once. Had a hot lead slip out of my hand and ground to metal for a millisecond. It toasted my ECU. A toasted ECU is not a performance enhancer. Trust me on that one.

Post an update after you poke around under the hood. I'll go nuke a bag of popcorn and wait patiently... whistle

1997 Sportage 4x4, auto-trans, Warn manual hubs, 4" UPYOURKIA front lift, TJ 106AA rear springs, 2-5/8" body lift, 31x10.50 treads, SmittyBilt SRC front and XRC rear bumper, swing-out tire mount, OBX LSD front diff, Track Finder rear locker, 5.38 R&Ps and... really crappy gas mileage! <img src="/forums/images/graemlins/shiner.gif" alt="" />