Trying to solve an ongoing problem
 

I own a 1995 Mercury Grand Marquis... I know it's not a Crown Vic, but it may as well be... The car has 132,000 miles on it, and there is noting special on it performance wise except a K&N Air filter.

About a month ago the check engine light came on after I had performed an oil change, and cleaned the air filter. I wasn't sure why the light was on, but the car was running fine. Then about a week after it came on I noticed that the car would die if I sat at a stop light too long (About 30 seconds or so). (I have noticed that if I put the car in neutral it does not die.) The car just basically shuts off. I can start it up immediatly, and when I do most of the time the car surges and chugs until I press on the accelerator. The car runs fine when I'm moving, and I only seem to have problems when I'm stopped.

I went to a local parts shop and they hooked it up to a computer. The first time she guy said that the car is running rich, and asked if I had started it without the air filter in. I said that I had just to back it out of the garage. He then told said, "That's probably what set the code. He cleared the code and said if it comes back on to go back. I left and on the way home the car died again. About three days later the light came back on so I went back. This time he told me that the car was running rich again, and then said that he thought my MAF sensor was bad. I asked him how much that costs and he said $100.00. I got out may hanes manaul and did some searching on line about the sensor, and I found out that sometimes people put too much oil on their K&N filter and it can cause the MAF sensor to foul. I got some electrical contact cleaner, and cleaned the sensor according to a site I found on line, and checked the voltages acording to the Hanes manual, it seems to be working fine. I cleared the code on my car, but it still dies under loaded idle. (And still surges)

Since this started I have put new spark plugs in the car, I put a new PCV valve on it, I have cleaned the O2 sensors (All 4 of them), and I put a new EGR valve on on the car as well as cleaned the EGR pipe.

Nothing I have done has made any difference other than the check engine light has not come back on for about a week.

Has anyone ever seen this before, or does anyone have any ideas what the problem might be?

RE: Trying to solve an ongoing problem
 

only use MAP sensor cleaner to clean the MAP sensor and yes the oil from the filter will cause dirt to stick to the sensor and throw it off. check the operation of the map and TPS too.

RE: Trying to solve an ongoing problem
 

Have had one where the fuel pressure regulator was leaking internally and allowing raw gas back into the intake. took me a while to find that one. just remove the vacuum line and pressure it up to check might solve your concern