Bad engine? Hope not!

Last fall My '89 K2500 suddenly came down with some engine malady. Snow and cold came so quickly that I could only work on it intermittently through the winter. Now, I have followed up on what I performed late fall and still the engine is not running well at all. I think I may have a bad cylinder... Help.

At first last fall I smelled an electrical burn. Truck would not run at all. Kept popping the computer fuse. I pulled the module (brain) and sure enough it was totally cooked. Replaced it and managed to get it to run. Then lots of snow and I left it till this past week.

Started yesterday... no power at all. Feels like it is not running on all the cylinders. Basic tune up was performed last fall (Cap, Rotor, Wires, Plugs). I am also getting an error code... O2 sensor. Have not replaced that though.

What should I do... compression check? Engine is a 5.7 350 TBI. What should the compression be in each cylinder... AT least ?

Any other suggesitons? Last thing I need is to replace the engine!... I fear that is where I am headed.

Thanks!

check yhat fuel is coming through both nozzels at the TBI unit when ideling, if not, try to cross the electric conectors on the nozzels.... if the other one works, your pcm has a defect.

Compression should be somewhere between 110 and 160, all cylinders should be within 5 lbs of each other.

You should also try to figure out what fried the computer before you burn up another one.

The amount of compression is really not as important as if they are all relatively equal. (yes the compression is important though) If they differ more than 5-10 psi in a particular cylinder, good chance your trouble starts there. HOWEVER......

If your computer is throwing an O2 sensor code, then this is a possibility. Your computer is sensing the engine is running lean, a false reading due to the bad sensor. The computer will try to correct its self by making the engine run richer. Thus making the engine choke itself to the point of running rough. The computer will through the code when it can not correct the problem itself. This is just a "could be senario" It could be your problem, it might not be I don't know without really seeing the truck.

Thanks guys... all good answers to check into before I condem the engine.

I appreciate your help!