4.3 vortec power loss & won't go over 20mph

Hi , anyone know what I can do about my 02 zr2 it won't climb a hill or go over 20 mph & only runs @ idle. I did a tune up plugs , wires, dist & cap. Coil , air & fuel filter Maf range control because that code came up on my comp readout . temp sensor & also pulled off 02 sensor on y pipe , but it got no louder w/o it. I am puzzled, the resonater makes a noise , but the backpressure on the tailpipe seems strong. It idles perfectly also .Any help would be much appreciated.

1. What brand and part number are the spark plugs?
2. What brand and part number is the distributor cap?
3. Are you certain the cap is wired correctly?
http://i561.photobucket.com/albums/ss58/cwhook/97newer43Lfiringorder-Copy.jpg


4. Did you use silicone dielectric grease on all terminals in the cap?
5. Have you checked fuel pressure and leakdown? If so, what were the results?
6. What DTC was set for MAF sensor?
7. Were there any other DTC's in memory?
DTC's tell you what circuit to check, that's all. They do not tell you to replace parts.

I will check these , but bought factory ac delco I believe . My economy is so bad that it got around 52 mi out of 3/4 of a tank. I have only been driving it 1 mile a day to get in my KW & back home. Hate being a prisoner of my zr2 , because I can't use it as a functioning , reliabe mode of transportation.Thanx for your time & generosity ; Harry

Hi , anyone know what I can do about my 02 zr2 it won't climb a hill or go over 20 mph & only runs @ idle. I did a tune up plugs , wires, dist & cap. Coil , air & fuel filter Maf range control because that code came up on my comp readout . temp sensor & also pulled off 02 sensor on y pipe , but it got no louder w/o it. I am puzzled, the resonater makes a noise , but the backpressure on the tailpipe seems strong. It idles perfectly also .Any help would be much appreciated.

remove the O2 sensor and go for a test drive..
check fuel pressure..use a guage ..

HI... This same thing happened to me in my 95 zr2 4x4 with the vortec engine... it was the day after getting semi flooded by hurricane wilma... if i remember correctly I had to replace the starter, the battery and the alternator after that storm so i think i discovered that the idle thing was due to low voltage making the truck run at idle to keep the fuel pump running... i know that i replaced the battery and the alternator at the same time and the truck ran fine after that... the starter had to be replaced due to salt water incursion... hope that helps...