I have a 1997 dodge neon the car is new to me it was running rough when i purchased it.I ran the codes with my computer codes po203 and code po300 and po303.I tested the maf sensor with a vacumn pump and a volt meter tested fine.Then I cleaned the throttle body and egr tube and egr ports all were fine looked at the idle air control motor but don't know how test it but checked for voltage and it had it .Tested the tps it tested fine check for spark on all cylinders with a spark tester fine check for resistance in the plug wire all good check coils with ohm meter was fine changed the spark plugs because I had a set the ones I took out look like the car is running very rich.Did a compression check all four cylinders are at 180lbs checked timing marks on the timing belt and they all line up.Next tested all injectors all have good spray coming out all at 12ohms .The car will not idle at all have to keep it around 1500 to 2000rpm to keep it running I have driven about 100 miles with no new codes coming up after I cleared them runs good on the freeway..The lady I bought it from said it ran fine before her son in law changed the water pump I am at a loss any help would be apperciated

 

My best guess at this point is that when he changed the water pump, the timing is off a tooth or two. Check that first.

 

That was my first guess I have checked the timing the two top arrows point at each other and the bottem arrow points at its mark dont know what to do.

 

Took the timing cover off today and put two drill bits in the holes on top of the cams indeed the exhaust side was off a tooth so got the timing se right now running smoother at lower rpms but still cant get it to idle it will sometimes level out at 600 rpm then die is there any way to raise the idle rpm thanks for any help it is surly appreciated...

 

IAC sensor on the TB controls the idle. If you create a vacuum leak does it idle smoother?

 

Changed the idle air control motor its idling well now so I took it for a smog test here in Cali pass with flying colors I am going to change the timing belt now because who ever put on the water pump didnt change the timing belt should i go with a gates belt ...thanks for the help

 

I will state that it may cost more for good quality parts, but in the end, if you want to make sure you don't have to do it again soon, you will spend the money now, or be peeved when you have to do it again.

I just paid the price for putting low quality parts on my daughters Suzuki Forenza by having to redo the water pump again - and the timing belt too - after only 30000 miles.

Your call.