Ok 99 GS with 180k miles. Never been rebuilt original miles. Cold start it acts like its got like a really bad misfire. And if motor isnt warmed up enough it boogs down really bad and has nooo power what so ever. Now when motor warms up it idles fine and you can 1/4 throttle it and get down the road but at 1/2 throttle it boogs and no power like its only running of 2 cyl.

now what came to mine was fuel pressure or maybe egr valve????

have you checked your ignition syetem?

Also, are there any obdII codes present? When was the last time any maintenance was performed? Parts replaced?

Have you tested your fuel pressure or checked your EGR valve? Why do you suspect those items? It helps if you come to the table with some facts and results from your own problem solving versus "best guesses."

Originally posted by CODE4
have you checked your ignition syetem? Also, are there any obdII codes present? When was the last time any maintenance was performed? Parts replaced? Have you tested your fuel pressure or checked your EGR valve?

^^This

Originally posted by CODE4
have you checked your ignition syetem? Also, are there any obdII codes present? When was the last time any maintenance was performed? Parts replaced? Have you tested your fuel pressure or checked your EGR valve? Why do you suspect those items? It helps if you come to the table with some facts and results from your own problem solving versus "best guesses."

well no i haven't checked those yet but i did all this 5000miles ago coil/wires were changed w/ ngk plugs. already check them there fine. complete exhaust system header to muffler including new magnaflow cat. )((O2 sensors haven't been changed)). ran a half can of seafoam though gas tank. 1/3 though crank and 1/3 though the vac system. all four rotors and pads. fuel filter. air filter.

now the only code that is on is the P420 CODE which has been on sence i bought the car 10k miles ago. Now i work shift work and my four days off start monday so im going to dig in alittle further to it. i want to take the egr valve off and tube and clean it... maybe its cloged up???? i dunno and check all if not replace all vacumm hose which i just might buy the good all 100hp red hose kit from RRM lol

I just wanted to get other output and see were else i can look at.

Proper procedure for troubleshooting this issue is plugs>wire>coil>computer.
I know exactly the problem your experiencing- its part of the reason that I got rid of mine because I could never pinpoint the issue and it got to the point of being unreliable.

Good luck!

ok so i had some free time to look at the car -- so i replaced the coil wires and plugs with the stock stuff and still had the problem --put the msd coil and wires back on and a new set of plugs and still same problem -- pin pointed the misfire is in #4 ((hooked to a better code reader that auto zones))

so am i looking at ignition/computer problems now???? or will a faulty injector make a misfire????

btw it only misfires at idle and passed 1/4 trottle .. if your crusing its perfictly fine runs awesome....

same time i did replace both o2 sensors (that light was on also) and did a radiator flush and new thermostat