Bucking under load

[jamesjk]

Hello all. I'm back with my 87 Corolla (post engine swap to 3AC). The engine runs great with 1 exception: Whenever the engine is under load such as moderate acceleration or up hills, the engine starts jerking or bucking and the performance of the engine suffers a lot. The more you step on the gas, the worse the condition gets. The car is totally drivable as long as there are no hills and you don't try to accelerate more than 20% of total capacity. (aka 0-60 in 10 min)

I've check compression, timing, and did a full tune up during the engine swap. I've checked the vacuum lines many many times and I even paid a mechanic to check the configuration of the lines.

Could a bad distributor cause this? How would I verify? Maybe the vacuum advance is messed up? The timing seems to advance when you rev the engine (verified with timing light)

Thanks!

[toyomoho]

Sounds like a fuel starvation problem. Check the fuel pump and filter.

[chefmarkf]

I agree. Does it stagger and backfire if you give it gas in nuetral? I had a bad pump in a 5a with similar problems. Tried everything from injectors, lines and distributor but in the end it was the pump.

[diver9000]

I think your rpms are maybe to low for the hill. You may have to give it a bit more revs to get up some of the hills. Check your dizzy and look to see if its worn out, if so replace it.

[jamesjk]

I thought I'd post this in case anyone else ever has this problem:

It was the catalytic converter. It was totally plugged. Poped a new one in there and it runs like new.