Lagging acceleration on 98 sw2

One thing it could be is fuel delivery could have a clogged fuel filter have you had a tune up lately changing the fuel filter, spark plugs Etc another thing it could be is your throttle position sensor there's multiple things that it could be do you have any codes have you checked your computer yet 4 codes give us more information thank you.

No codes. Just replaced the head assembly due to a blown #4 valve.. New plugs & wires, replaced vacuum house , cleaned the ignition coils, replaced crankshaft position sensor as well.

Maybe that was a bad head job that you had done could also be a bad crank sensor might be wrong sometimes they're bad when you buy them might want to try to replace it again that might be an easy fix? At this point we're both guessing right? Which vacuum hose did you replace? I would say take it back to the shop that did the valve head job and most likely they can figure out what's going on? Good luck with that.

We ordered the head and did the work ourselves.

And you confirmed that's the right head for your car and when you said you cleaned the coil packs are they seated correctly everything's installed correctly sounds like you have a power loss?

Yes & yes

Car sounds great, starts right up just lagging on acceleration. Will go from a stop, just no speed for passing and now shifts at higher rpms. Picture of engine put all back together

I've had people on here tell me that they had a clogged fuel filter and it caused a lot of problems with fuel delivery have you done a full tune up changing all your filters your fuel filter air filter Etc?

Haven't changed the fuel filter yet. Checking for a plugged cat now.

Yeah yeah plugged catalytic converter right could be? looks like you have an after-market air filter on there I don't know if that would cause any issues? How long have you had that aftermarket air filter on there cuz I think they have to be channeled to the outside so they suck in enough air to go in the intake.

Not cat have noticed now that car engine revs up to 2k on its own at start up then settles back down to 1100 to idle

Well that leads me back to questioning your throttle position sensor because that's supposed to work with a computer to control your idle and when I had one bad on my SC2 it would do this erratic idle up and down you know surging and stuff it controls your take off and slow down of your engine when you're driving so it might have a lot to do with your acceleration problems might just be your throttle position sensor?

Shouldn't it then be throwing a code?

That's true you think it would be, kind of strange all you could do is maybe take it off the car clean it look at it actually I don't think you're supposed to clean it but make sure your throttle body is clean your intake you know try to make sure you've covered all your bases as far as everything being tuned and cleaned out especially with your fuel delivery.