96 GP SE, Engine sick.

[mmcfearin]

My 96 Grand Prix SE is having a list of issues but I think some or all are related. Milage is 143,000 and had a full tuneup at 125,000. Temp is in normal range.

This is my wife's daily driver, and she says it just feels like it is running "hard" Unfortunatly I upgraded to a Benz 6 months back and I think any other car runs hard now so I really am a bad judge of that now but i think it is.

Most of the time have to pump the gas pedal a few time to get car started, it will sometimes imediatly stall out.

Idle seams to be poor and teaters on stalling out.

MPG has gone down the drain, not sure exact numbers but used to be so good on milage and now its no better then my 92 Explorer.

When driving mid range power feels perfect but when excelerating past 3000rpm engine boggs out and nearly stalls if I don't let off the pedal engine will stall.

Where should I start?

 

[JESSEGOTTA GP GT]

Fuel filter would be my first guess.

 

[blueguy]

MPG's out? What motor is it? I'd say the converter might be going out...could be clogged. Also could be a MAF issue...Might try Seafoaming it too.

 

[cerick08GP]

Well, definitely replace the fuel filter. They are super cheap and easy to do.
That being said, I’m pretty sure it is your fuel pump resistor causing most of your issues.

 

[mmcfearin]

Ok today I drove it all day to get a feel of it, I used a can of seafoam in the fuel and replaced the resistor and fuel filter. No luck so far and I was rong with the RPM, it drops out just under 4000RPM
Driving it today i fell it really has poor exceleration up till about 40mph then its nice and zippy up to 80mph where I stopped that test. At highway speed it felt smoth and performed well but on street roads and at low speed it just feels rough, like i was running with no oil, just feels wrong and sounds dry, just lacks its old smothness. while driving today it also once had what I would call a mechanical hickup, the car was running well and around 20 mph the engine just kinda jerked like a frew cylinders said, "nope not today" only happened once but i sure noticed.

 

[JESSEGOTTA GP GT]

could be a clogged cat, but i think it would still run crappy at higher speeds? maybe a clogged fuel injector? my old firebird starting running rough and I had a tune-up done, ran worse, so i replaced the coils, nothing. replaced the ICM, nothing. replaced both o2 sensors, nothing. took it to the shop to have a new cat put on, and all it was that the shop crossed a few spark plug wires, so maybe have the smaller parts checked out before you start replacing bigger more expensive parts.

 

[cerick08GP]

So your saying nothing changed? Does it still start hard?
At this point I would recommend you get your car scanned for codes. Autozone will scan it for you pro gratis.

It could be several other items. Without knowing the cars history it is very difficult to narrow down the choices. I would first check the spark plugs. Pull out a couple of the easy ones to get to, and see how they look. If they look good, I would guess move on. One clue it might be the plugs is if your car uses oil. The oil can foul the plugs. The next thing to check is the MAF sensor. Unplug it, and see if you car runs better. If it does run better (not perfect), the MAF sensor is bad. And the last likely cause is the catalytic converter. If you have never replaced it, you have gotten 20k more out of it than it was designed for. You can check this by taking a drive at night. Get the engine really warm, actually get on it a bit. Stop in a dark area, and pop the hood with the engine running. Look at the exhaust pipe just above(in front) of the catalytic converter. If it is glowing red, your cat is shot. With any luck at all it will be one of those three, maybe.