Well here we go!
I just replaced the exhaust system with Magnaflow cat and muffler new pipes etc. I did some more fixing like new rear calipers and water pump and stuff. But it wont pass the emissions test! What causes it to have too many Hydrocarbons? It is running at about 600 when its supposed to have 300. Everything else is way below.

Next problem.

Having said I replaced the water pump. I figured it would stop overheating because the water pump was clearly out. It did not however. So I got some radiator flush and did that. Yes, I follow instructions very well. The gauge still indicates that it is overheating. But the gauge acts weird. It flicks up and down randomly and sometimes reads wrong temps. Is it possible that it could still actually be overheating? If so should I replace the radiator?

Next problem is when the vehicle completely warms up it starts to stumble. RPM's at all speeds and idle jump up and down. When it is cold it is very steady. When it is warmed up it loses alot of power. Any idea's?

 

Not much on emissions help, but I'm sure a search would get you some good ideas.

Next problem.

[/B][/QUOTE] Having said I replaced the water pump. I figured it would stop overheating because the water pump was clearly out. It did not however. So I got some radiator flush and did that. Yes, I follow instructions very well. The gauge still indicates that it is overheating. But the gauge acts weird. It flicks up and down randomly and sometimes reads wrong temps. Is it possible that it could still actually be overheating? If so should I replace the radiator?[/B][/QUOTE]

My first reactuion is to the sending unit, due to the erratic readings, radiator would be last on my list of "replaceables" unless I knew for sure

[/B][/QUOTE] Next problem is when the vehicle completely warms up it starts to stumble. RPM's at all speeds and idle jump up and down. When it is cold it is very steady. When it is warmed up it loses alot of power. Any idea's? [/B][/QUOTE]

I'd sirst scan for codes.

Also would be a good idea to use a scan tool on it while driving to see what information the ECM is getting/using.

Ya, not a lot of help, but there's a bucnh of possibilities from a simple tuneup, to one of the many sensors....that's why a scantool is the weapon of choice.

 

It's possible your AIR pump is out that would prevent sending air to burn the excess hydrocarbon coming out the exhaust or the diverter valve is bad which will cause the same thing. The diverter valve is easy to replace. If the ignition is weak it will cause all of the symptoms you list, most likely a coil going bad. Basically your not burning all of your fuel.

Overheating, welcome to Houston, I'm running a Be-Cool radiator with dual Be-Cool fans to keep my beast cool. I suggest getting the tuneup right on the engine then see if it still overheats. Try a new sending unit first and try scanning the car to see if it's really overheating.

Stumbling, power loss, bad idle, sounds like too hot or again ignition. A degrading coil as it gets hot gets worse as resistance goes up.