What would cause a lack of rpm's?

My truck runs between 1000 and 2000rpm all the time, through all gears, going 90km on the highway it sits at around 1800. When I hit a hill, if I step on it, it will surge up a bit and start to go, then rpms will drop drop with power loss.

In park if I rev it, it will go up higher but at like 3000 + it starts to pop/backfire.... I thought it was plugged cat or something so I put on a new exaust from the manifold back, same thing... I have done seafoam, and a motorvac.. dont know how to do a compression test so I dont know what else to look at..

I have done all the basic stuff fluids, tune up etc... only other thing I havnt checked is timing, it idles at about 500 rpm smoothly.

The engine has 300 000 + k's on it so should I just think about a new engine/trans or what?
If so where should I look in canada?What kinda prices should I expect?

Thanks

95 F150 XLT 2wd 302 E40D
309 000km's

 

I would inspect that the spark plug wires are put on in the correct order first, make sure the air flow from the intake of the air box, through the filter, through the duct to the throttle body, and so on until you can't see or feel past the throttle body, isn't blocked. Make sure you are getting adequate fuel pressure, change the fuel filter if you didn't. You should be able to hear the fuel system pressurize by listening for a faint whine or buzz just as you turn the key from off to on (not start) If you can, bring #1 cylinder up to top dead center on the compression stroke and see if the rotor under the distribution cap is pointing to where the #1 spark plug wire terminal would be if the cap is on. You can do this for each and every cylinder, if you wish. But still, the popping sounds like a timing/spark plug wire issue.

 

I agree with tomcat make that your first plan of attack but timing sounds reasonable and wear and tear may be a factor as well. I had an old chevy c10 that something similar with the loss of rpms and it was that my compression rings were failing while mile oil rings were fine keeping it from burning to much oil and still having a loss of compression.

 

Ok thanks guys I will try that.

what is the best way to get cylinder 1 to TDC, would removing the plug and sticking something down there, then hand cranking the engine till it pushes whatever I stick down there to the highest position be good enough?

Also where would I hook up a fuel pressure gauge to test it?

Thanks

95 F150 XLT 2wd 302 E40D
309 000km's

 

Yes that would be a way to find TDC preferably using something non metal and something that won't leave anything behind. I'm not quite sure where to hook up the gauge on a 302 i have the 300 but just follow the fuel lines up.

 

Remember it's the compression stroke - there are two tdc in one cycle - you have to be on the compression stroke - the fuel pressure valve is on the fuel rail on top of the injectors looks like a tire valve - dont put an air pressue gauge on it - that is real gasoline it's pumping in there