I have a 98 malibu 3.1 with 145K on her. Bought the car about a year and a half ago with 118K. It has run great until now. It is hesitating and stuttering badly. It feels like it has no power at all especially when trying to go uphill. Also, I can feel the engine stumbling or missing when I'm sitting at a red light. It feels like it's gonna stall but never does. No check engine lights or anything. The plugs and wires were fresh when I bought it-could they be bad already? Also, it makes an annoying clunk when i'm off the accelerator. Not all the time but at seemingly random times, never when on the gas though. It sounds like the transmission clunk you get when you park on a hill with the wheels turned and you take the car out of park and put it in reverse. I don't think it's the tranny though because it shifts perfect and the fluid looks good and is at the right level. Sounds like something in the front end. The cv boots look great though. Probably replaced before I bought it. Maybe a ball joint or something??? I have been reading this forum and you all have helped me with many other little problems with this car. (Ex. wheel hub and bearing, blower motor resistor, max a/c button) I hope someone out there can help.

If you have an ohm meter check each plug wire for continuity. If you don't pull each plug wire and check each each plug. They should be grey if firing properly.
Another thread on misfire has directions on how to ohm the coils, and check the module. Advance auto checks modules free.

have the plugs ever been replaced ? 100k is the max. If they look like they have not it is time to. I would also replace the wires too, even if you think the plugs are new. Use only AC delco for both.

Update on hesitating malibu: I finally got a check engine light on the way home from work.(after about 2 months of this hesitation) The code was a p1404 which my handy chilton's manual says is the EGR valve stuck open. It gives a procedure for checking the resistance at the EGR electrical connector which I'll do when I get home today. 2 questions. Could this be causing my hesitation? and Is there anything else I can check pertaining to the EGR short of a replacement?

Take off the egr valve and clean it good spray some silicon on it check the diaphram that it isn't ruptured. Some times this will work until your new one arrives a couple of days.
I have noticed them causing hesitating in a hilly area at 30 to 40 mph in traffic.

yes clean it , it may also have a gasket to replace to
as far as the silicone NOOOOOOOOOOOOOOOOOOOOOOOOO:nono:
NO SILICONE it will kill your OX SENSOR. DO NOT USE CARB CLEANER EITHER
Get a can of TB cleaner ( throttle body cleaner)

the egr recycles exhaust gas back to your manifold, it may only do it at start up when yor engine is cold an running in open loop b4 your heated ox sensor warms up enough to be reliable, then yor engine goes to closed loop and runs off of the ox / 02 sensor. so the egr may be hanging open. if the pintle looks like it is al the way down, put it back on and unplug it ( make sure ign is off). see if it cures the hesitation . may still run bad.

I'm aware about 25 or 30 years ago silicon was taking out a lot of oxygen sensors. They came out with a computer safe silicon. The lead has been removed from the new silicon spray I thought this was what damaging sensors. I have used silicon spray on the shaft on my own 02sensors and I haven't had a bad one on my cars. I always put new ones on a customers car. What information do you have on silicon.

Thanks for the info. I did not know that. I just heard and saw in print, do not use Silicon spray, they never said why. I thought it was strange in a way, who could silicon spray damage an 02 sensor ?. Does it say on the can 02 sensor safe ? I always use assembly lube anyway.

The spray can states that no lead is used but it doesn't say O2 safe.
I emailed valvoline pyroil silicone spray and asked them. The site said I would be contacted in a timely manner.
Valvoline said they never tested it but don't recommend it.