I have a 87 4x4 w2.8 it shudders going up hill on the highway when i give it gas I have to floor it for it to kick down and it stops
I did tune up,fuel filter dont know what to do

 

shudders?

as in shakes? stutters as far as misfiring? like too lean or too rich? no power?

 

A couple of things come to mind. Is the kick down linkage adjusted correctly. Is this a carbureted vehicle, you could have a problem with the needle inlet valve, float adjustment or accelerator pump. If it is carbureted it might be time for a rebuild.

 

its throttlebody and it just seems like it always wants to be in overdrive i floor it and it goes but shudders going back into over drive only wants to go when i floor it but it only does this on the highway

 

no power and i did also replace the cat

 

I have an 89 GMC Jimmy that I purchased new and has been my daily driver and has almost 440,000 miles and runs and drives great. In the past when I had issues like yours I ended up replacing both injectors. However, injectors run around $65 ea. So I would hate for you to spend the $$$$ and not solve anything. It does sound like it is fuel related. When was the last time the fuel filter was changed? It could be Throttle Position Sensor, Injector, Fuel Pressure Regulator. TBI needs about 11 psi to run normal. A scan tool can check TPS voltage from idle to WOT. A fuel pressure tester can measure the pressure from the pump. In the life of my car I have replaced the TPS, IAC, rebuilt my TBI unit with a kit from NAPA, replaced the injector pod assy and replaced Injectors. The difficult thing to do is to check fuel pressure on the TBI cars as there is no test port. I purchased an inline fuel pressure test kit for TBI a long time ago. I would break the line at the fuel lines at the front frame before they travel up to the engine compartment and install the gage between the fittings and measure the pressure with the engine running. I have since installed an permanent in-line fuel pressure gage at the TBI inlet from CFM Technologies.

 

Ive finally found the problem...............
It was a bad PCV !!!!!!!!!

 

Glad you found the problem. I was curious how you determined it was the PCV. That is one of the items I would not have suspected. I know it is appreciated when someone has a problem and reports back with the resolution. You never know who might benefit from your resolution.

 

I read this article plus it was making a lot of noise so I was going to replace it anyway

Loss of Gas Mileage
This is often the first effect of a bad PCV valve. Your gas mileage will go way down, and you have to fuel up way more often.

Loss of Power
Another significant effect is the loss of engine power. This is especially evident when you are trying to go uphill while accelerating. You engine feels like it has the performance of a lawn mower engine, instead of a regular engine.

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Rough Idle
Because the crankcase gases cannot escape, a back pressure builds up inside the crankcase. The engine then has to fight itself to run, and this results in a very rough idle.

Sputtering or Coughing
When you try to accelerate, an engine with a bad PCV valve sputters or "coughs;" it feels like the engine has stopped for a brief moment. Again, due to a back pressure buildup, the engine has to fight itself to run, and sputtering is the end effect.

Hesitation
Hesitation occurs between sputtering and a loss of power. It feels like sputtering, but lasts longer than just a brief moment. According to AutoZone, hesitation may an effect of a clogged or damaged PCV valve or clogged hoses that connect to the PCV valve.

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Read more: The Effects of a Bad PCV Valve on a Dodge Dakota | eHow.com The Effects of a Bad PCV Valve on a Dodge Dakota | eHow.com

 

On my 89 GMC Jimmy I had a plugged PCV port on the throttle body but the car ran normal with the exception of blowing oil out of the dipstick tube if it was not seated all the way. The PCV would also pop out of the valve cover. In addition, the oil pressure gage would register 60+ PSI. I did replace the PCV and the hose but it did not resolve my problem. I could not figure out what was wrong for a very long time. I decided to rebuild the TBI and during the rebuild process I found the plugged port in the TBI unit. Once I reinstalled the rebuilt TBI unit oil pressure was once again normal. Thanks for the response to the symptoms for the PCV failure. I will keep that in my memory bank for future reference.