I had a similar problem with severe bogging and wanted to put this out there for the next guy looking for answers. My 2002 Protege5 was once my pride and joy. Now at 130,000 she is my old swayback mule. I want to get every mile out of her but spending as little as possible.
She burns oil like Saddam leaving Kuwait, half a quart of oil or better per tank. The smoke is worst when first started in the morning. I see others writing of the same issue. I blame the oil rings. Some blame the valve guides. Compression is a bit low in #2 cylinder but those bad rings arent going anywhere soon. I just think of her as sort of a hybrid 4stroke 2stroke that uses a little oil in the fuel.
Have had duct tape on the air intake pipe accordian area for several years. I change the tape as annual maintenance. I had a CEL showing both O2 sensors had a heater fault P0031 and P0037. Still drove it like I stole it.
On highway I noticed a sudden lack of top end power. She was unable to maintain cruising speed of 70 going uphill. Next time I drove her she hesitated a bit above 3000 rpm. It got worse every day. In the end I had to finesse her to get her to get over 20-25 mph. She also made a whirring sound that sounded like it came from the power steering pump. The sound pitch matched the revs.
Replaced plugs. Old plugs had heavy white deposit (resembles calcium deposits). I imagine this is from the burning oil.
Continued to drive her real slow until the performance degraded beyond my suffering/laziness ratio. Then I started working through the symptom troubleshooting from the service manual. "No. 12 Lack/Loss of Power-Acceleration/Cruise" page 01-03B-31
I changed the bad o2 sensors with no effect on performance except to clear the CEL.
I replaced wires and coils. No effect.
Changed air filter. No improvement
Searched for vacuum leaks. Replaced duct tape and trimmed the hard end from a stiffened leaky vacuum hose. No noticeable effect.
I checked cam sensor. No apparent problem.
Cleaned off and checked the gap on the Crank sensor. Still no love.
No brake drag.
PCV fine
EGR too hard to get to. So...it must be ok. Right? I thought of maybe hiring a small child to get it out but decided to wait.
VICS seems fine
VTCS seems fine
Thought that maybe the timing belt had skipped a tooth, so I broke down and changed it with new idler, tensioner, spring, and waterpump for good measure. The old belt with at least 70,000 mi looked almost new and was still in time.
I wanted to measure the fuel pressure but was wary of using a standard fuel pressure gauge due to the fuel line connections. I also was looking into changing the high pressure fuel filter. The live sensor data showed that the long term fuel trim was always being trimmed down occasionally by -25%. This told me I was running rich which indicated not a weak fuel flow, but strong or even too strong.
I thought about the fuel pressure regulator, but I need the pressure guage to check that too.
Then, I described the problem to a friend who said he had similar symptoms on a Toyota that turned out to be a clogged catalytic converter. When I checked my exhaust flow with my hand over the tailpipe it was noticeably weak.
I the removed the exhaust manifold and the front cat. The cat was completely glazed over with a thick layer of carbon over the ceramic substrate honeycomb. The exhaust was blowing by the manifold gasket at the #1 port. The leak was right behind the power steering pump and was the source of the whirring noise I thought was a bad bearing or something. The manifold to cat gasket experienced severe blowby cutting it into three segments.
I figured I'd be buying a replacement Cat so I pried on the substrate with a screwdriver and cracked off a chunk. The fragment showed that the clogging did not extend more than about an eighth of an inch down into the surface. The honeycomb below that was clear. I decided to crack off a thin layer of the ceramic all over the top surface. Then I used air to blow out the cat from the outlet toward the inlet. I blew out the dust and the air passed straight through with little resistance. I reassembled the exhaust and cranked her up. Problem solved, sort of, and now she runs great.
After a short trial I may replace the cat with one of those $200 49er units I see online. Or I may just wait to see how long it takes to clog this one up again.
