98 SaturnSL1 engin races in park and neutral engin lights on& off

It seems like the problem lies with the engine management system, rather than the brakes. Given that you've already replaced the MAF, MAP, and TPS sensors, here are some other things to check:

1. Vacuum leaks: Inspect all vacuum lines for cracks or damage that may be causing a leak. A vacuum leak can cause erratic idling, poor acceleration, and stalling.

2. Idle air control (IAC) valve: The IAC valve controls the engine's idle speed. A malfunctioning IAC valve can cause the engine to stall during idling. Try cleaning the IAC valve with carburetor cleaner and see if the issue is resolved.

check for spark first,either with a spark test light or the old fashion method- screwdriver held close to metal,if no spark- distributer could be the culprit

Did he clean the throttle body - plate . TPS - throttle position sensor . Check for vacuum leak ?

May be the Idle air Control Valve (IAC) . Suggest you do the search for both the TPS and IAC. There's a wealth of info on how to test, clean replace the sensors on the 3.8 engine.

What does scan data show ? Do you know what that is ? What do the fuel trims show , is the computer adding or taking away fuel ? Are the O2 sensors switching normally ? EGR valve stuck open . When you replaced the IAC did you clean the passage ? On a scan tool what are the IAC counts ? Is the the PCM controlling it .Did you clean the throttle plate ?
007 Idle Speed Problems Scan Data for Idle

check to make sure airfilter is ok and maf sensor is clean. then check out tps ( throttle position sensor ), here are a few causes of a bad tps sensor--- transmission shift issues, bucking, jerking, idle surging, engine cutoff, hesitation on takeoff, surge while cruising down highway. if light on dash is on get it scanned to find problem code. most auto parts stores will do this for free. auto-zone etc. here are a few symtoms of a bad maf sensor-- surge, slip condition underload. the mass air flow sensor may be degraded or contaminated. stalling, misfiring, poor acceleration. ( a check engine light may not come on ). a lot of times just by cleaning maf sensor cures the problem. GOOD-LUCK!

p0171 and p0174 are o2 sensors, There are 4 o2 sensors on a Taurus. 1 on each exhaust manifold, and 1 after each catalytic converter.
p1518 is vehicle speed, idle speed control----this means the idle air control needs fixed. you can take it off and clean carbon from it. do not push on end of air valve it will loose its adjustment. do not put in any liquid to clean, the best way is to clean end of valve with an old toothbrush or similar. also clean carbon from engine side where iac mounts. when clean put back on. you can use carb cleaner for end of valve, as for the 02 sensors, you have to find out which ones are bad first. or replace all thats up[ to you. you have to get a 02 sensor socket for 3/8 drive. then they just turn out. the best way to get them out is have the car warm.

hmm

try turning the ignition on,, let it sit for 30 seconds ,, switch it off and then start ,,,

if it works then your fuel pump is sending too low pressure,, change the pump...

if not then change the IAC valve and the oxygen sensor and the engine coolant temperature sensor..

HI,
You may have some carbon build up in the throat of the throttle body itself. That buildup may also have plugged a small air hole in the throat. The carbon build up keeps the throttle plate from fully closing against the stop.

I would try to clean the IAC with a little CHEMTOOL and see if that helps first.