Car wants to die when accelerating

I have a few ideas of what may be the problem, but wanted to put all the details up to see if anyone has suggestions.

Car: 2000 Grand Am 2.4L 4cyl (automatic transmission)

Symptoms:


Car idols fine. I could let it set at idol and it will never die.
When I am at stop, and when I begin to accelerate the car fails to go, sometimes die. If it doesn't die, when I press the gas it won't go and then all of a sudden jump and go.
Once the car is going, there doesn't seem to be any problems, unless I begin coasting and then begin to give it gas again. Then it does the same as if it was stopped and then accelerating.
I'm not sure if this is an accurate symptom, but it appears to be worse when it is wet outside. Note I say it is seems worse, on bright sunny days (with low humidity) it still does it on occasion, but it accelerates better, and sometimes I don't even notice an issue.

If the wet air is an accurate symptom, my guess at the problem would be something with the distributor cap. Are there any other possibilities? Are is there anything else to consider when replacing the distributor cap? And if possible what would be your estimate for time to fix myself?

EDIT
Check engine light is on. The code that came up was P0420 - Catalyst System Efficiency Below Threshold (Bank 1).

Someone mentioned transmission, but 99% sure it's engine issue.

So obviously catalytic converter is an option of problems. What else could there be.

Also how difficult of a job is it to put a new catalytic converter on? I know someone that could possibly work on it, but don't want to ask if it would be too much of a job.

About 3 months ago I replaced fuel filter and spark plugs, because I was having issues (new spark plugs was the solution).

when I press the gas it won't go and then all of a sudden jump and go.
Sounds more like a transmission problem.

when is last time you tuned this up? like gas filter, plugs, wires,plugs,air filter? you may want to check vaccum hose also. by the way does your check engine lite come on? here's few other things dist cap,rotor button, also could be fuel pump going out so i would try gas filter before you worry about pump.

good luck...

Welcome to AF!!

After reviewing your car's symptoms you may actually have a transmission issue not a problem with the engine. The fact that you say it doesn't want to go when you give it gas, does the engine rev up and then it jumps and goes or do you mean it will not rev up? If the engine RPM goes up and the car sits still the transmission has an issue. If the engine does not rev then the issue could be a blocked exhaust or partially blocked exhaust. It could also be an issue with the fuel delivery system.

One other thing your car does not have a distributor cap. It has a distributorless ignition that uses a crank position sensor, an ignition module, coils and plugs.

You also don't state whether your check engine light is on or not. If it is you should have the car scanned as the results will help pinpoint the problem.

Check engine light is on. The code that came up was P0420 - Catalyst System Efficiency Below Threshold (Bank 1).

Someone mentioned transmission, but 99% sure it's engine issue.

So obviously catalytic converter is an option of problems. What else could there be.

Also how difficult of a job is it to put a new catalytic converter on? I know someone that could possibly work on it, but don't want to ask if it would be too much of a job.

About 3 months ago I replaced fuel filter and spark plugs, because I was having issues (new spark plugs was the solution).

The code you mentioned usually indicates that the cat is bad and will need replaced.
Go to Rock-auto.com and search for a new convertor assembly. This is a couple hour job if you have a lift or easy access to the under side of the car. Parts will be in the $200 range for a direct fit cat which is the best way to go. Good Luck!

So a direct fit would be one that you bolt on? Compared to a welded on?

What are your reasons for saying a direct fit is better?

Direct fit usually eliminates welding of the new convertor onto the old pipe. It also makes things simpler because it is a bolt on and does not require welding and cutting although you may still have problems with the bolts. I suggest you spray all bolts with PB Blaster before you start disassembly. This will make things much easier.

If you intend to keep the stock exhaust a direct fit will work best although it may be more expensive it saves a lot of time. You can find a magna flow convertor that will work and probably save some money but you will need to cut the old pipe and weld the new convertor in. If you have a welder you can do it at home if not it will cost you to have someone weld it up for you. You can do it on the car but it would be better to remove the assembly so you can get to the top to complete the weld.

Not totally familiar with your engine, but you can also take the rubber snorkel off of your throttle body and see if it is dirty. If it is all gummed up, you will have hesitation when you first step on the gas. If it appears black, get some carb cleaner and spray it up. Get a rag and wipe out the filth. If there's a throttle plate, make sure it moves freely. Hope this helps.