So I've had my plymouth neon for months now and it has had problems occur and they have went away randomly one morning. But this latest problem is seeming to get worse. So the problem is when I start it, it runs fine. But as soon as it heats up and gets to operating temp, I can't not get it to accelerate properly. It will get up to about 25mph and start losing power and rev, go out, rev, go out, rev, go out, but it will stay at 25pmh. And when it's doing this every like 5 seconds I hear and feel a deep sounding knock. Now this does not happen everytime, sometimes it will drive fine/ most of the time. But it seems everytime I come to a stop, the problem will occur. And when it does do this the more I press the pedal, the more it decelerates. But I've learned that it I throw it in neutral, turn off my car, wait a sec and coast, turn my car back on and put it in drive, my car will run fine and even get up to 70mph no problem but as soon as I let off the pedal and try to push back down the problem will come back. I am no mechanic and I have little to no money. And sometimes I can drive it for miles and come to several stops and the car runs fine. Please help me

 

I did not mention the check engine light is not on and I have turned the key on off 3 times to get code and the check engine light still won't come on

 

I think your catalytic converter is clogged. When it drives fine, the clog is not blocking the exhaust. The knock could be the mass of melted metal bouncing around in the catalytic converter.

The check engine light should come on as soon as you put the key in the ignition and turn it to the on position without starting it. If it doesn't, either you have a problem with the gauges (which a vast majority do) or the bulb is burned out (or taken out by the previous owner).

You can check to see if it is the catalytic converter easily. When you are having the problem, pull over and look under the car towards the back of the engine. The catalytic converter will be glowing red hot if it is the problem. I also suggest taking it to a parts store like autozone to have the trouble codes checked. They will check them for free and get you the parts you need.

 

Do u have a number I can call to diagnose my problems further? No codes came up when I took it to autozone

 

The problem is intermittent but I can basically tell when it's going to happen. When I start my car it's fine, drive it around and when it shows it's starting to warm up the problem will happen. Rough idle, not wanting to accelerate, and when it is not wanting to accelerate if I push the pedal further it bogs down more, throw it in neutral the engine will rev fine, turn the car off and back on and put it bck in drive it will pick up as expected. But when I let off pedal entirely it will have said problem again. And when said problem is occurring if I try to force pedal down it will have an odd pop/knock sound that I can not locate. And it happens just once. But after about 20 minutes of driving and I park to go in the store, come out my car will run fine for quite some time no problems. I found a fuel pump relay was ghetto rigged and I changed it, seemed to help for the rest of the day, but I was driving around for awhile. But normally every morning I can tell when it will happen. I need desperate help as I have a job 30 miles away for $13hr and I do not want to show up late or not at all due to problem eventually progress (if it does), I've had the problem for a month and drive my car daily, I can not afford a to not drive it. Please please help