My 98 GC has a couple of problems that I hope you folks can diagnose for me:
1) It loses power on steep climbs. On the freeway going up a long stretch of incline it's just fine. Yet on steeper hills where I go hiking the speedometer slowly and steadily drops down. When I step on the gas, nothing happens. Even the RPM needle stays constant. Sometimes I'd hit the foot of the incline at 60 MPH and within ten seconds it drops down to 45 MPH with me pressing on the gas pedal.

2) When I step on the gas a little aggresively from (whether I'm cruising or from a dead start) I hear rapid clicking noises under the hood. It sounds like a playing card on bicycle spokes almost. If I press harder, the noise gets louder. I thought at first it was just bad gas. But I've only been using premium from different gas stations with fuel additives thrown in lately. The noise is still there. Somebody mentioned it could be my fuel filter.
Could that be it? Where is it located on the 98 JGC 5.9?

I hope you good people could point me to the right direction before my baby falls apart on me halfway up the hill on me.

SGT Al

You need to have your Fuel Pressure Checked with a Guage could be starving for fuel.Could be a filter ar your Fuel pump going bad. The clicking noise could be your fuel injectors, do you notice a miss or just a lack of power?

Sounds like it is "pinging" to me. Detonation "ping" is the fuel in the cylinder exploding rather than a controlled burn. This can be caused by a lean mixture, (yes, check fuel pressure but also could be egr, vacuume leaks etc) over advanced timing, low octain fuel (bad gas), high engine temps and excessive carbon build up.

There are also three TSBs for your symptoms:

- 09-05-00 - leaking intake manifold oil pan gasket.

- 18-48-98 - shorting spark plug wires.

- 18-34-97 - PCM reprogram.

(source www.alldatadiy.com)

I have a 99 JGC and started making a similar noise. Dealership told be it was about to throw a rod. I had to replace my engine. $5,000.00. I hope that it was not something as simple as what they are saying in the responses.