95 silverado 5.7L tbi with lots of aftermarket parts. I just got it running again, I changed the IAC, ignition coil, plugs, and orings for the injectors. I finally got ...

95 silverado 5.7L tbi with lots of aftermarket parts. I just got it running again, I changed the IAC, ignition coil, plugs, and orings for the injectors. I finally got the leak to stop, the fuel pressure lowered and now when I drive it, it has no power anymore. I could sit and a light and punch it and it would peel out nicely. Now it boggs really bad and when on the highway it just doesn't want to move. I have the pedal floored and it's not doing anything. It doesn't have that varooom when something opens up and plants you in the seat. The speed will go up, but it takes a lot longer than it ever did. I don't think I could pass a yugo right now. I took it up to over 80mph, but it's really slow. Something is wrong and I'm not sure what. I can check for vac. leaks, but it seems like more than that. It starts up fine and it idles fine and it moves fine when your not mashing the pedal. It will drive fine when you want to cruise, but won't perform beyond that. This truck was pretty fast and now it's a dog. What can I do to get my truck back?

Never underestimate the faults of a vacuum leak!! Are you getting any codes? Hows it act on cold start?

no service lights have come on yet, so I don't know of any codes unless I take it to advance auto. Hot or cold it starts up just fine, nice smooth idle around 600rpm, it just lost all of it's power, like something is holding it back. It never bogged this bad ever.....

You don't have to take it anywhere to get the code. Look under your steering wheel down to were the dash panel stops you will see a 0bd1 plug.(pictures on google) two rows of little holes with metal contacts inside. if you take a paper clip and jump the two top far right squares- turn the key to the on position but dont start it, it will give you the code. the list of codes can be found on google anywhere. you should get 12 three times then if it senses the problem, another code or more. blink-pause-blink-blink means 12. blink-blink-pause-blink means 21. get it? This may tell you the problem right away it might not tell you s*** but its definitely a good place to start. I'm having a much similar problem with my 94. Im working on fixing the third code to pop up now. Youd think I had a beer bong hooked to the throttle body dumping the gas in.

I sprayed and checked for leaks with no luck. Not sure where to go from here, except see if autozone will check for codes. I have no check engine lights, so I don't know if they will or not.

Ok I'll bite. Plugged catalytic converter?

how would I check something like that??????????

The first thing I would look for is evidence of exhaust backing up through your intake. It usually puts black soot on the clean side of your air filter. They also make a tool that screws into your oxygen sensor hole and you attach a pressure gage................when you accelerate the engine and see back pressure, it indicates a problem. I cannot remember how much pressure is bad, maybe 1.5 pounds or more. You can also look at manifold pressure (vacuum) as you drive and if it stays real low as you accelerate slowly it may indicate a problem. Obviously if you floor it then the vacuum will drop, thats normal as it accelerates. You also could have the converter removed for a test to see if the performance improves. Do NOT remove the oxygen sensor and drive it to see if it gets better because the hot exhaust will burn and melt underhood items near the open exhaust hole. I hope this helps!