How can you tell if your motor is locked on a 1998 Chevrolet Malibu 4 cyl.

You may have a coil failure or spark plug failure on #3. Swap coil and plug of cyl#2 with cyl#3 and see if problem moves to cyl#2. If so, it will be a plug or coil. I wouls recommend changing both

sparkplugs have heat ranges, you need to stick with ac delco for those.

Could be.
Could also be a problem with the idle air control valve.
Even fuel pressure or a dirty air filter.

try a new catalytic converter. Had this on a 2002 Malibu.

closest to the engine.rear exhaust manifold on v6.in the exhaust manifold 4 cyl.

There is a temp door actuator motor that is not working,it is on top of the blower box,where it is mounted,the dash will have to be removed to replace the actuator motor.If this was at all helpful,please rate,thank you.

buy some engine oil dye at any auto parts store
a uv lamp will be needed to use to locate the leak
this works best with newer cars and so many things in the way

It is located at the rear of the engine between the timing cover and exhaust manifold. You will have to remove the manifold to ge to pump. It runs off the timing chain. It would be a wise decision to take to an experienced mechanic.

are the plugs gapped right!!---3.1 v6 is 60---2.2 is 42 and 2.4 is 50 thousands, for 98 through 2000 4 cylinder models, most of the malibus take platinum plugs,

Hello rsscott50

I hope you have this thing fixed but if not you can try this.
First I need to assume the "lock cylinder" will turn with the correct key installed.?

You must turn the lock cyl to the run position. I suggest disconnecting the battery first.

I pull the radio out to gain access to the ign. switch.

If you have a small mirror it will really help to find a small square hole in the top of the "plastic" part, "the ign. switch".

If replacing only the lock cylinder you will NOT need to take the 2 screws out holding the plastic piece to the dash.

You will need a tool of sorts so once to locate the small hole on the top of the ign switch and also have the lock cyl rotated to the run position, you press the tool into the small hole.
Tool--can be about the size of a medium screw driver--but the end will have a bend, a right angle bend and the bent piece approx. 3/8" in length.

You will be pressing down on a button help there by a weak spring, look on the new lock cylinder.

As you press down or inward pullout on the lock cyl.
It's that easy.

After installing the new lock cylinder, if that is what your are doing, you might not be able to start the car.
Most chevys have a chip built into the lock cyl. with a sort of password--if the car doesn't see the right password it wont start.

Question: if you need further instruction please let me know.
If the Lock cylinder does not turn, then the fix has another & different approach but you can do it.

Good Luck,
Dave