Rough Idle - Codes P0151, P0174, P0300

scan for codes and make sure you clean throttle body and IAC hole on both sides. fuel should be 60-66 psi so you are good there. auto parts scans for free. it could be a broken spider assembly in intake causing this as they early ones had problems like that.

Is the spider a difficult thing to replace?

the top of the intake has to come off, but it may not be that. they are about $300.00 as well. it could be anything until you get it scanned for codes. also you cannot block off the throttle because it is getting no reading from MAF so will stall.

It did not stall out with the MAF disconnected.

My 99 tahoe has a rough idle at start up when you drive it for 20 min or so it will go a way its been doing this every winter for the past two years. In the past I put seafoam in and fixed the problem.
I have not put it in this year. what is causing this problem it is running rich leaking out of tail pipe

Running rich:

Probable causes include a bad O2 sensor, excessive fuel pressure (bad fuel pressure regulator or plugged return line), leaky fuel injectors, dirty air filter or restricted air inlet, or a defective coolant sensor that prevents the engine management system from going into closed loop mode.

of course it wont because when you do that it goes into what is called open loop and sets engine up to run rich. scan for codes auto parts does for free.

how would adding seafoam help any of those things

Adding that chemical in there at times can make things worst-troubleshoot the items I've mentioned-

I was coming off a bridge and when I fully stopped, the truck started lurching violently forward and even a bit of side-to-side. The "check engine" light flashed rapidly on and off before it stalled. I was able to restart it, the "check engine" light steady this time.

Whenever I'm idling at ~500 RPMs, the truck starts lurching again; above 1500 RPMs, it's as if there's no problem at all.

Oil pressure is fine, the battery is new, the engine isn't overheating, and there's no smell from under the hood. My computer is telling me the #4 cylinder is in need of maitenance, but a compression test is showing me it's not a broken valve. The spark plugs have been replaced, so I'm wondering what else it might be. Someone recommended it might be a "spider injector" problem. If this is the case, what kind of expense am I looking at to replace it? Is this even a valid diagnosis?

On the ignition coil, switch #3 to # 4 and # 4 to # 3. tell me where the misfire is now?

The misfire is still occuring between cylinders 6 & 2 (ie, the new #3 and the old #4).

what is the original codes for the misfire.
I thought it was #4 only.
do you have random misfire?

I have a 1995 chevy tahoe that sat for about 5 yrs.
I changed the fuel pump,spark plugs,and the fuel filter, but it still runs rough. Starts find but idles rough and studders rreal bad when on the trottle. it has a 5.7 ltr throttle body injected. what else can i do to try to fix the problem.

Hook up timing light remove air cleaner so you can shine timing light at fuel spray. start up spray pattern should be 360 deg and fine spray. Any drips or loss of 360 pattern the injector pentil dirty from old gas deposites. Try some fuel system cleaner it may help. If not replace inj.

I just bought this Tahoe a week ago, it has done great until now...now it smokes and the smoke smells like antifreeze and the engine idles rough. Please help with any advice possible...

Coolant is leaking into the combustion chamber could mean headgasket, cracked head or block or intake leak-Get it block and pressure tested. Are you overheating?

It only over heated once and never did get into the red are on the gauge.it basically just idles rough and smokes...